5 Step Sisters Vol. 1 Chapter 1

 The Invader of the Detached House

The moment I snapped my eyes open, I—Rikuto Miyanaga—realized my blunder.

The position of the sun, visible through the wide-open curtains, was much higher than usual.

Checking the smartphone lying by my pillow, the time was surprisingly 12:30 PM. A new personal record.

"Crap. I slept too much..."

Raising my upper body, I slowly stretched. I let out a lazy yawn, and tears sloppily blurred my eyes.

It was the first weekend since I advanced to my second year of high school. Having spent a week since the class reshuffle, it seemed I had accumulated a fair bit of fatigue. Well, I didn't make a single new friend, and I don't have plans with anyone, so oversleeping doesn't particularly cause me any trouble...

I sluggishly dragged myself out of bed and headed down to the first-floor washroom while scratching my belly. Outside the window, sparrows were chirping lightly at each other, as if making small talk.

Saturday, April 12th. The weather was a spring-like clear sky. Until late March, there had been days with temperatures that made you wonder whether to wear a T-shirt or a knit sweater, but the season was finally shifting toward spring.

I washed my face, brushed my teeth, and, looking at myself with strange bedhead in my bangs, visualized the contents of the refrigerator in my head. Brunch would be pancakes with apple jam. I had a bag of baby greens left over, so a green salad would be fine on the side. Maybe I'll make omurice for dinner for the first time in a while...

As I gargled and spat into the well-polished sink, I thought about how, in the end, I hadn't gone cherry blossom viewing this year either. Well, it probably would have been boring to go cherry blossom viewing alone anyway.

As I was wiping my wet mouth with a towel, a drawn-out electronic chime rang throughout the empty house.

It probably wasn't the neighborhood association's circular board, since I had just passed it on. Sales, religious solicitation, or maybe Dad ordered a delivery?

"Yes, yes, coming..."

Knowing the person couldn't hear me, I gave a domestic-sounding reply.

Flapping my slippers along the floor as I entered the living room, the camera-equipped intercom screen displayed a man in a gray uniform I recognized from commercials and around town.

"Good morning, Miyanaga-san. We're the Anteater Mark Moving Company!"

Recalling their catchphrase, 'One-shot catch with a long tongue! We diligently carry without eating!', I tilted my head in confusion. What business did a moving company have at my house?

"Miyanaga-san?"

I replied, "I'll open it right now!" for the time being, but looked down at my outfit and grimaced. It was a wrinkled pajama look that obviously screamed "just woke up."

However, deciding it would be worse to make them wait, I gave up and hurried to the entrance. But I don't usually lounge around lazily until this time, today is actually a rare occurrence... Making excuses in my head, I slipped on some sandals and opened the front door.

What leaped into my vision was the blue sky. White clouds—and the even whiter teeth of the nice guys.

Faced with a refreshing dazzle even cooler than the commercial, I reflexively shielded my eyes with my hand. This wasn't the amount of light one should be exposed to right after waking up.

"Hello! Beautiful weather today, isn't it!"

"Y-Yeah."

The two muscular men were working together to lift a tall cardboard box. Huge. I wonder what's inside, I was thinking, when the guy in front, who had been doing all the talking, flashed his teeth and spoke.

"Well then, we'll go ahead and carry the luggage inside!"

"Eh? Um, wait a mi—"

"Carrying it in~!"

"...Please do!"

Crap. Why did I say please.

But by the time my easily-swayed self came to my senses, it was already too late. Sporting smiles so pleasant they practically sparkled, the guys slipped past me as I stood there paralyzed, breaching the entrance. While taking off their shoes skillfully without using their hands, they delivered the final blow.

"We'll be taking this straight up to the third floor!"

"Eh? Eeeeeh?"

I was bewildered, wondering if they hadn't mistaken my house for someone else's. But I also felt like the guy had clearly said "Miyanaga-san" right at the start.

My house—the Miyanaga residence located in Kusanagi in the southern part of Shizuoka Prefecture—has a layout where there are stairs immediately upon entering the entrance, and a door to the living room on the left. It's a design considerate of individual privacy, allowing one to go to the upper floors without passing through the shared living room space, but since I'm pretty much the only one living in this house, there are zero opportunities to appreciate it.

The guys went up the stairs with careful yet swift movements.

Left behind near the entrance, I was dumbfounded as I poked my head outside. Beyond the wall, I could see a four-ton moving truck parked on the road in front of the house.

Then, right after, a passenger car entered the premises. It was my dad's beloved car, a red BMW.

Naturally, Dad was in the driver's seat. Deepening my confusion further, I waited for the car to stop in the carport before walking briskly toward it.

"Dad, what is the meaning of this!?"

The door opened, and my dad—Mukai Miyanaga—stepped out of the car. Setting aside his driving sunglasses, for some reason he was wearing a bright red aloha shirt, even though he was supposed to have just been on a business trip to Tokyo.

"Oh! I'm happy you came out to greet me, Rikuto, my son!"

Quickly taking off his sunglasses and slipping them into his shirt's breast pocket, he spread his arms wide. I dodged the suffocating embrace from my father, who was returning for the first time in three weeks, by shifting my body to the right.

"Enough of that. What is all this?"

Saying "this," I pointed at the truck.

Looking disappointed, Dad corrected his expression, rubbed under his nose, and declared.

"Well, you see. Actually, your dad has decided to get remarried."

".........Come again?"

"Hmph. Weak reaction."

Dad pouted his lips. When a man in his mid-thirties does a gesture like that, it's not cute at all; it just sends shivers down your spine.

"In other words, I'm having the moving company bring in the belongings of my new wife and her kids."

"No, wait a minute. New wife? Her kids...?"

I held my head, feeling dizzy at the unfamiliar words. Then, perhaps realizing his lack of explanation, Dad gave a wink and added.

"Today is a lucky day on the calendar, so it's the perfect day for moving."

—This is hopeless, I thought.

The conversation was hopelessly failing to connect. No, it probably made sense in Dad's head, but my common-sense understanding couldn't keep up.

Dad was always like this. He didn't do things like putting them in logical order or laying the groundwork. Acting as if to say, Gah, how tedious!, he just pushed forward at full throttle, and whether it turned out good or bad, he'd just spit and laugh it off with a cheerful boast. To begin with, he supposedly eloped with my mother, who passed away when I was little, and married her here in Shizuoka. That's the kind of guy he is, living purely on momentum.

However, even for me, who had been watching his unapologetic back for over ten years, this morning's events were an incomprehensible and unprecedented situation.

To tell the truth, I had actually anticipated his remarriage for years. This might include some bias as his biological son, but I think Dad is fairly popular with women. His appearance is a bit scruffy but he's a ruggedly handsome guy; he's tall, and his well-trained body is toned without a gut. His profession is a sales rep for a major electronics manufacturer, and he flies all over the country, and sometimes overseas, all year round. His loud voice, his dynamic nature, and his tendency to go straight ahead once he sets his mind on something are slight flaws, but depending on the person, they might see those as the charms of Mukai Miyanaga.

Still, the reason Dad had remained single until now was probably out of consideration for me, his only son.

That's why, normally, this should have been good news. I should have been able to bless it from the bottom of my heart. If only I hadn't been informed like this, without any prior warning whatsoever.

"—Well, in short, Rikuto, you're not only getting a stepmother, but a stepsister too. You did it!"

"Don't say it like it's killing two birds with one stone! It's way too sudden!"

"My motto is to go out and meet good fortune head-on."

Dad let out a cheerful, booming laugh with his deep voice, and I finally covered my eyes with one hand.

"At least let me sleep and wait it out today. I'm not mentally prepared. I want the movers to go home too..."

The "Eh!?" that rose from the direction of the entrance probably belonged to the movers. Dad yelled back, "Don't mind him!" before turning back to face me.

"Can't do that. The plan was originally to make it in time for the opening ceremony, but it didn't work out due to our mutual work schedules. In exchange, I've properly completed the school transfer procedures, notified the neighborhood in advance that the moving truck would be blocking the road, and I'm about to hand out Tokyo souvenirs as an apology. No one can resist the charm of Tokyo Banana, after all."

"Why is the groundwork perfectly laid for everyone EXCEPT your son! Usually, it's the other way around!"

"Dad felt a little shy about it, too."

"Don't feel embarrassed over weird things!"

Just as I retorted, a new passenger car entered the house's premises. It was an unfamiliar Toyota Voxy. I could see a woman in the driver's seat, but the rear seats were mostly obscured by dark gray glass.

The pure white Voxy smoothly passed over the gravel path and backed perfectly into the carport. It slid effortlessly into the left space Dad had left open, as if it was the most natural thing in the world.

It was like a game of matching shells. Or a wedding aisle. The parking technique, as if complementing each other's missing or lacking parts, felt like a show being put on for me, the bystander... Or rather, feeling that way over a simple parking job might be bordering on paranoia, but in short, at this moment, an ominous premonition was surging in my chest like rough waves.

"H-Hey. Is that car..."

"Yeah. It seems your step-in-law-mother and step-in-law-sister have arrived."

Dad nods solemnly. You can just say stepmother and stepsister at that point, right?

The sound of an engine stopping came from the carport. In contrast, my heart started playing an explosive beat, and my completely tense body was naturally trying to do an about-face.

"Sorry. I was supposed to go to the Shizuoka Festival today."

"The Shizuoka Festival ended last week."

Dad slowly stroked his short beard and looked at me with gentle eyes as I was on the verge of fleeing.

"I'll tell you this upfront, but you don't have to force yourself to think of them as a mother or a sister. Though, of course, your dad would be happy if you all got along."

If you just clipped this part, it sounded like a good line from a father who doesn't force things on his son.

I mean, her kid is a sister? There was a time when I longed for a sibling, but young me had absolutely never envisioned a modern, hardcore relationship like being step-siblings.

But no matter how much I complained, reality wasn't going to budge now. Besides, despite all my grumbling, my dad's remarriage itself was a cause for celebration above all else.

"...Anyway, congratulations on your remarriage, Dad."

Upon hearing my brief congratulation, Dad's face lit up brilliantly. Seeing that innocent, child-like face, my words of complaint mysteriously retreated.

"Yeah! Thanks, Rikuto!"

At that timing, the sliding door opened, and multiple people got out of the car. I flinched, but Dad performed a theatrical bow in their direction.

"Ladies. Welcome to our home!"

Dad has a wild appearance, but such a pretentious gesture actually suited him. The one who let out a soft chuckle was undoubtedly my dad's new wife.

"Mukai-san. Geez, what was that?"

Standing there was a woman so youthful and beautiful, you wouldn't believe she was the mother of a child.

Her height was probably in the low 160s. Short-length hair. Intelligent eyes. She paired a striped blouse with neat white pants that showed her ankles. How to put it, she had the atmosphere unique to a highly capable career woman.

When our eyes met, the woman softened her cool gaze.

"You must be Rikuto-kun. Nice to meet you, I'm Natsuki. I've heard a lot about you from Mukai-san."

"N-Nice to meet you."

I hurriedly bowed my head in greeting. I bet he hadn't told her anything decent.

The woman who introduced herself as Natsuki-san signaled with her eyes to the people standing behind her.

"Without further ado, I'll introduce you to Rikuto-kun."

At that moment, I wanted to beat my dad to a pulp.

Because the prior information and the scene in front of my eyes did not match up at all.

"My twin daughters, Mio and Karin."

—My stepsister is a pair of twins!?

If that was the case, tell me that! It's the most important detail!

And surprisingly, the ones standing side by side were incredibly beautiful sisters.

First, the first one. The one called Mio was a girl with wavy hair styled in a bob cut.

Big, slanted eyes as clear as a lake, white porcelain skin, and cherry-blossom pink lips—each of her features was unbelievably well-proportioned. She was dressed casually in a baggy hoodie and shorts, but it was obvious at a glance that she had a curvy figure.

"!"

When our eyes met, she looked down bashfully, nervously rubbing her thin legs encased in black tights together. How to put it... she's very modest. It makes me feel embarrassed for some reason, too.

Next, the second one. Karin, standing next to Mio, was a girl with glossy hair tied in twin tails.

Her pale, thin knit sweater seemed to emphasize the lines of her slender body, giving off a mature allure. Her buttoned skirt was extremely short, and her fingernails were decorated with flashy nail art. She had the appearance of a refined, modern girl.

They both had almost the same height and build, but their faces weren't very similar. Fraternal twins, perhaps?

Then, Karin, who was playing with her smartphone, glanced at me and muttered quietly.

"That bedhead is awful."

".........!"

That casual remark dealt a lethal amount of damage to my heart.

That's right. I got so toyed with by Dad that I completely forgot, but my bedhead was exactly as it was. Or rather, I was in pajamas. I looked exactly like I just woke up...

To meet my dad's new wife and her kids for the first time in such a sloppy state—how shameless could I be? The main culprit was definitely Dad, who neglected to contact me, but I couldn't help blaming myself for letting my guard down and sleeping in just because it was a holiday.

As I hung my head powerlessly, Mio lightly pulled on the sleeve of Karin's clothes.

"...Hey. Karin?"

"But it's the truth."

It seemed she thought I was hurt and reprimanded her for my sake. As I was struck by the kindness of a girl whose name I only just learned, Dad let out another booming laugh.

"From now on, you'll be seeing Rikuto's bedhead until you're sick of it. So brace yourself, Karin!"

It looked like a follow-up from a family member, but it just pushed me right over the edge. Giving a reply that was a heavy sigh itself, Karin went back to playing with her phone.

Even so, I discreetly observed them. The twins who were supposedly becoming my stepsisters were completely different types of beauties, and what's more, they looked to be around my age.

Even one would be too much for me to handle, yet there were incredibly two of them. Spending time under the same roof with beautiful girls—just hearing the situation makes it sound like a manga or a drama, but in my case, instead of a reward, it felt like a punishment game.

That's because I have no immunity to girls. Of course—and it's very humiliating to preface this—but I've never had a girlfriend either.

The only member of the opposite sex I had spoken to properly in the week since the opening ceremony was a childhood friend who ended up in the same class as me for the first time in four years. The world is heartless.

—However, I must admit that my understanding was far too naive.

Originally, I should have realized it sooner. Because the luggage currently being carried in by the movers was by no means... an amount for just three people.

Towards our deadlocked spot, lively, pattering footsteps approached.

Turning in that direction reflexively, my eyes widened considerably.

"Amaaaazing! Is this our new house, Sorane's new house?"

Running over with sparkling eyes was a child who looked to be in kindergarten or early elementary school.

She had straight-cut bangs. Her hairstyle was a low ponytail, neatly braided. Her light clothing—a T-shirt with a bear print and half-pants—suited her cheerful smile perfectly.

"My, what a large house. The chic exterior is wonderful, isn't it."

Holding hands with that child was a girl wearing a frilly dress. Her voluminous, wavy long hair swayed softly in time with the movements of the girl, who was probably a middle schooler.

And, finally.

Walking behind them with slow steps was a girl dressed in a clean white blouse, a yellow cardigan, and a classic floral skirt.

"Make sure you two don't trip."

She was tall for a girl, and her facial features were intimidatingly well-ordered. More than anything, her strong-willed eyes were striking. In her long hair tied in a side tail, two cherry blossom petals were attached, as if to color her, as if to bless her.

Suddenly, a strong wind blew. Someone let out a small scream. The girl's skirt billowed out like a dream, and the petals on her head fluttered away as if sucked into the sky.

Faced with a somewhat ephemeral and fantastical sight, I murmured almost unconsciously.

"A cherry blossom spirit...?"

The voice was too quiet, and shouldn't have reached anyone's ears. But the girl, who had been holding down her hair and skirt, raised her face as soon as the strong wind died down and stared challengingly at me, standing at a distance.

Her small, petal-like lips played a clear voice.

"...What?"

"N-No. Nothing."

I had no courage to repeat nonsense in the face of her sharp gaze, so I answered evasively. It seemed she wasn't quite the pure and innocent girl her appearance suggested.

Looking back later, this was my memorable first meeting with the five sisters, but... at that time, I wasn't carefree enough to be focusing on something like that.

"Sorry, Mom. Sorane and Fuka said they wanted to see the weeping cherry tree over there up close."

"No, it's fine. Thank you for accompanying them, Chinatsu."

While letting the exchange between the cherry blossom spirit-like girl—Chinatsu—and Natsuki-san wash over my ears, I swallowed hard.

It was far more than just two.

My dad's new wife's kids... there were five of them.

◇◇◇

My mind was completely consumed by confusion, but there was no time to sit around and talk leisurely after that. Natsuki-san and the others were asked to be present by the moving company.

It seems that having someone present on-site is a fundamental part of the moving process to prevent troubles like lost or damaged belongings. Dad and the others arrived later than the movers, but since they were told that I, a resident, was home, they had started the work without any issues.

Natsuki-san and the others went to supervise, Dad went on an apology tour around the neighborhood carrying Tokyo Bananas, and the youngest two of the five sisters were exploring the house, making a fuss with comments like, "It's huge!" and "It's so spacious!" During that time, I made myself presentable. I didn't have the mental leeway to cook in the kitchen, so I quickly finished a brunch of two bananas.

After about an hour and a half, the carrying in of the luggage was completed, and the movers, having accomplished their job, took off their hats and showed refreshing smiles.

"Well then, thank you very much! Have a good new life!"

The sight of their backs as they got into the truck and left was cool, giving off the vibe of true professionals, but putting that aside.

—Summoned by Dad, the eight of us were gathered face-to-face in the living room.

Well, rather than a living room, in the Miyanaga household's case, it's an LDK (Living, Dining, Kitchen). Opening the door right by the entrance reveals the living room with a sofa and TV in the foreground, and further in, a kitchen and dining table with a sweeping view of the yard from the south-facing windows. The overall impression is kept from being too sweet by using dark colors for some of the walls and furniture, while basing it on a nuanced white wood grain.

Thanks to Dad's earnings, we live a fairly affluent life, so it's quite spacious—in a word, you could say it's a bright, open, and stylish space. Perhaps because of that, the women were looking up at the vaulted ceiling in admiration or gazing out at the yard where evergreen trees grew.

It was great that the house seemed highly rated, but I already had a point I wanted to interject about. We use a long, narrow ceramic dining table—either Italian or British-made, which Dad was particular about—but... the number of chairs lined up there had doubled.

Even though there were only four chairs, including the ones for guests, as of noon, now there were even heads of the table set up on both ends, making it possible to seat a maximum of eight people. Of course, it was Dad who ordered the extras. Why is he always so thorough and well-prepared only when it comes to things like this? I was getting genuinely annoyed.

Seated to my immediate right was Dad, and at the head of the table to my left was Chinatsu. Sitting directly opposite me was a restless Mio. The sisters seemed to be seated clockwise in order of age.

Even so, the idea of this many people gathering in our usually dead-silent house felt like I was dreaming. If only that were the case.

Also, what was the source of this sweet scent that had been tickling my nasal passages for a while now? It had this... soft and fluffy kind of fragrance, but... was someone wearing perfume?

"You were surprised, weren't you, Rikuto-kun?"

"Gah!"

Spoken to suddenly, I let out a weird yelp. Leaning forward over Dad, who was leaning back in his chair, Natsuki-san furrowed her brows and spoke to me.

I panicked, wondering if she had seen me flaring my nostrils just now, but what she said was about a completely different matter.

"Mukai-san didn't tell you anything, did he?"

She asked in a tone that suggested she hadn't heard it from the man himself, but was absolutely certain of it. Just from that, the realization that Dad was really going to marry this person flashed through my heart. Natsuki-san was already well-acquainted with Mukai Miyanaga's recklessness.

"Ah... yes."

When I nodded timidly, Natsuki-san sighed with an "I knew it." Receiving her heavy glare from the side, Dad let out an exaggerated, fake cough.

"Now then. Since we're all gathered like this, let's introduce ourselves again!"

Wow, he blatantly changed the subject...

"I'm Mukai Miyanaga. I work in sales for an electronics manufacturer, and I'm constantly flying all over the country and overseas. It's not like I learned anything specific when I was young, but I like moving my body. Lately, I've been enjoying learning various martial arts from people I've met. I look forward to living with all of you."

Saying that, Dad flashed his teeth and smiled.

I completely thought that everyone besides me had already met, but the five sisters were glancing at Dad and exchanging uneasy looks. ...Huh?

I leaned in slightly and asked Dad in a low voice.

"Hey, Dad. I highly doubt it, but... is this your first time meeting them too?"

"Yeah. I only just met Chinatsu and the others face-to-face during breakfast this morning."

My doubts hit the mark.

If that's the case, the situation between me and the five sisters was almost exactly the same. Realizing that we were all being dragged around by this unpredictable man made me feel a slight sense of affinity.

"I told you about Mukai-san and the remarriage early on, didn't I?"

After saying that with an exasperated look, Natsuki-san placed a hand on her chest.

"I'm next. Once again, I'm Natsuki. My maiden name is Sugiyama."

Hearing maiden name, I thought, Does that mean they've already registered their marriage?—but I asked about the part that caught my attention.

"Since it's Sugiyama, does that mean you're originally from Shizuoka?"

It can't beat Suzuki, but there are quite a lot of families with the surname Sugiyama in Shizuoka as well.

Then, as if she had been waiting for that, Natsuki-san showed a friendly, charming smile. It was an expression so attractive it made my heart skip a beat.

"Spot on. I moved to Tokyo when I went to college, and I've lived there ever since. About six months ago, I met your father... Mukai-san, at a bar, and we hit it off. It was a coincidence that he lived in Shizuoka, though."

A bar... six months ago... There were many things I was curious about regarding how they met, but I decided to hold back for now. There would probably be opportunities to ask later.

Even so, she was a woman whose cheerful way of speaking and approachable smile left a strong impression. Just as I was thinking I might be able to get along with Natsuki-san with a good sense of distance, she casually added another piece of information.

"Also, my profession is a lawyer."

I see. Her approachable yet flawless atmosphere made sense once I heard her profession was a lawyer.

"Rikuto, if you ever have any trouble, feel free to consult me anytime."

"That's very reassuring."

When I smiled slightly, Natsuki-san's face broke into a broad smile.

"Then, could I ask you to introduce yourself?"

"Yes. Umm... I'm Rikuto Miyanaga. I started my second year of high school this spring. Nice to meet you."

While saying that, I bowed my head.

Even I thought it was a safe and uninteresting self-introduction. It was fresh in my memory that I had given a similar greeting in my new class, just omitting the middle sentence. I had agonized until the very last second over whether to add that my hobbies were reading and watching dramas, but ended up saying nothing. Plain hobbies are somehow hard to tell people about.

Nodding with a smile, Natsuki-san shifted her gaze next to me.

"Chinatsu, are you ready?"

"Yes. ...I'm the eldest daughter, Chinatsu. I'm sixteen."

Chinatsu bowed her head toward Dad and me. At that moment, her tied-up long hair slid down smoothly, as if stroking her slender shoulder.

Making eye contact with her small hair whorl, I reflected that I should have added my age too.

The eldest of the five sisters, Chinatsu. With somewhat sharp features, she probably resembled Natsuki-san the most. Her straight posture and polite way of speaking conveyed that she was a well-mannered honors student.

"I-I'm the second daughter, Mio. I'm fifteen, a first-year in high school, and Karin's twin older sister..."

Following up with a voice that seemed about to fade away was Mio, who was fidgeting in her seat. I already know that you're a good girl.

"Third daughter. Karin."

Having finished speaking with few words, Karin didn't even move her eyes from the smartphone in her hands. Her attitude blatantly showed that she had zero interest in her mother's new husband or his kid. It was almost refreshing.

"Next is me, then."

Giving a small, polite cough, Fuka took her turn.

"Good day, I am the fourth daughter, Fuka. I am thirteen years of age and have become a second-year middle school student. My special skill is singing, and my favorite pastime is listening to music. I look forward to our acquaintance."

She bowed with refined movements and smiled gracefully. ...It was my first time seeing someone speak with such a high-class, lady-like tone in real life, but coupled with her clothes, she looked like a sheltered young lady.

"Sorane! Six years old! Fifth daughter! First grade!"

The youngest sister, Sorane, energetically held out five fingers and one finger to show "six years old," then alternately thrust her left and right hands forward while saying "fifth daughter" and "first grade."

"Ah! I like soccer! I do!"

Perhaps having concentrated too much on managing her fingers, she quickly tacked that on at the end and smiled, showing her white teeth. ...It somehow warmed my heart.

When the self-introductions concluded smoothly, Dad put a hand to his chin, looked around the table, and said earnestly.

"Goodness, even so, you are six beautiful sisters."

"My, what a flatterer."

Natsuki-san smiled, putting a hand to her mouth. It was a reaction that showed she was used to being told that.

Because honestly, I didn't think Dad's words were purely flattery. Even if they had been introduced as a family of entertainers, I wouldn't have been that surprised. That's how brilliantly clear and stunning their beauty was; they seemed somewhat otherworldly.

No, what was detached from reality was this sight itself. From today, it seemed I was becoming family with this exceptionally beautiful mother and her daughters. Even trying to remind myself of this fact, it didn't feel real at all.

"By the way, Chinatsu-chan, when is your birthday again?"

Dad casually asked. I didn't miss how Chinatsu's shapely eyebrow twitched.

Most likely, the way he familiarly called her "Chinatsu-chan" grated on her nerves. It wasn't like they had opened their hearts to their brand-new father yet. In fact, their psychological resistance was probably stronger than mine, as a guy.

"...I was born in May."

"Then Rikuto, who was born on April 2nd, will be the older brother to all five of you!"

"Oh, is that so. Please take good care of these girls, Rikuto-kun."

"R-Right."

The two adults were getting excited on their own, but there's no real older brother or sister with only a month's difference.

"Besides, Rikuto-kun, you can cook, right? I even decided to remarry Mukai-san after hearing that."

Is she... joking? For a joke, Natsuki-san's eyes were strangely serious, and Dad, for his part, had a look that said, "Wait, this is the first I'm hearing of this."

"Because actually, Chinatsu and I—"

"Mom. Isn't it about time you went shopping?"

The one who cut off Natsuki-san's words like slicing a piece of paper was Chinatsu. Glancing at her watch, Natsuki-san's eyes went wide. "Oh my, look at the time."

Saying "Heave-ho," Dad stood up.

"Well then, we'll leave the rest to you six young ones, and Natsuki and I will head out to buy some things. We'll go around to the supermarket and the drugstore!"

"Eh."

After unintentionally letting out a voice dripping with tragedy, I hurriedly covered my mouth. I mean, I've never heard the phrase "leave it to the six young ones" before.

Please don't leave me behind, I wanted to plead, but Dad wasn't perceptive enough to sense my inner screams. On the contrary, as soon as our eyes met, he threw an arm firmly around my shoulders and whispered. So suffocating.

"—Rikuto. Just because I'm not around, don't go pushing Chinatsu and the others down."

"Are you an idiot...?"

I wanted to look up to the heavens. Your son is neither energetic nor thoughtless enough to push down a girl he just met—let alone someone becoming his stepsister.

"Just hurry up and go..."

"Hahaha. Man, you're cold."

Dad and Natsuki-san went out together. A little while later, the sound of an engine echoed from outside.

In the space where only the children were left behind, I swallowed a lump of saliva.

Perhaps because the adults who had been at the center of the conversation vanished, a chilling silence filled the living room.

Just as I was wondering what to do, Chinatsu, sitting to my left, crossed her arms and declared.

"First, you're probably wondering, so I'll let you know. Our mother will share a room with Mukai-san on the second floor, and we will be using the third floor."

She had her eyes dropped to the surface of the table, so I didn't realize it at first, but it seemed she was speaking to me.

Even so, her vibe was different from a few minutes ago. Her lack of expression hadn't changed, but there was an intimidating force in her cold, authoritative tone.

"Ah, is... that so."

Even though we were in the same grade, my intimidated self ended up using formal language.

There are three private rooms on each of the second and third floors, and I use one of the rooms on the second floor. The other rooms on the same floor are Dad's study and bedroom, so that must mean the latter will become the couple's bedroom. Since there aren't enough rooms, the five sisters must be sharing, but there was no way I could know their room assignments, nor did I have the courage to ask.

Then, Chinatsu finally looked at me.

"So, as we'll be living in the same house, I want to establish some rules."

"Rules, you say?"

"Yes. Isn't that obvious? We're step-siblings, sure, but we're also of different genders."

Brushing up her hair, Chinatsu said coldly. What she said was completely reasonable. For boys and girls of our age to smoothly live together, clear rules are necessary. For our mutual peace and tranquility as well.

"More importantly, why are you using polite language? You're a month older, right?"

"That's, well... true."

I consciously relaxed my shoulders. In reality, my tension was only increasing, but it was clear that the conversation wouldn't progress at this rate. After all, there was no one here to back me up.

"First, I want the third floor to be off-limits to boys."

That was exactly what I expected. As sisters, it was only natural for them to be wary of guys.

"Since there are restrooms and washbasins on the first and third floors respectively, I don't think it's an unreasonable demand."

"...Yeah. I always use the first floor, so it's fine. To begin with, I normally only go up to the third floor to clean."

When I agreed understandingly, Chinatsu pulled her chin back in agreement.

From there, it became a time to align on various items—mainly regarding household chores.

"As for laundry, I guess I usually run it after taking a bath. It's a machine with a drying function."

"In that case, we'll run ours late at night, like we always have. Should we take turns cleaning the lint filter for the dryer?"

"Yeah. You can leave restocking consumables and such to me for a while."

"Just tell me the brand names and that will be enough. I looked at the garbage collection calendar too..."

Like this, the conversation proceeded without a hitch. While prioritizing my methods and schedule, I was grateful that she gave her opinions at every step.

And what I understood from this conversation was that Chinatsu, like me, handled household chores on a daily basis. Most high schoolers leave the chores entirely to their parents, and wouldn't even think about cleaning the washing machine's filter. Since Natsuki-san said she was a lawyer, she was probably away from home a lot, just like Dad.

Moreover, in Chinatsu's case, she had four younger sisters. The hardships of being the eldest daughter were unfathomable to me, who had no younger siblings. Chinatsu likely had similar impressions from our conversation, but she never let any empathy towards me seep into her expression or tone of voice.

"What time is dinner? We'll shift our time so we don't get in your way."

"I usually start cooking around 5:30 PM on weekdays... I guess. Broadly speaking, I take a bath around 7:00."

"Then we'll start eating after 7:00."

Hearing Chinatsu say that decisively while taking notes, I vaguely thought, I see. Of course there wouldn't be any idea of eating together.

I almost misunderstood for a second, but this discussion wasn't about sharing chores and cooperating. Chinatsu was implicitly hinting—"Let's not get involved with each other."

"..."

At that moment, Mio raised her face as if she wanted to say something, but she just mumbled in her mouth and no words came out. Karin was languidly staring at her smartphone, Fuka just smiled pleasantly, and none of the sisters besides Chinatsu interjected at all.

"Zzz... Zzz..."

As for the youngest, Sorane, her upper body was swaying as she nodded off. She was already bored and asleep. Just what you'd expect from an elementary schooler.

A sharp tension ran through the discussion when the topic moved from dinner to the bath.

"The bath will depend on the day, so I guess whoever wants to go in can go first. The person who takes a bath first will be in charge of cleaning the tub."

"...Does that mean this guy might soak in the tub after I've taken a bath?"

The one who interrupted Chinatsu's statement was Karin.

At her phrasing, the corner of my mouth twitched. I certainly don't possess the refined hobby of doing anything with the leftover bathwater a high school girl has been in.

"I rarely drink plain hot water, though."

When I cracked a joke, Karin glared at me fiercely.

"...What is that supposed to mean?"

The one who stopped moving her pen and tilted her head was Chinatsu. It seemed she didn't quite understand the meaning of our exchange. She looked back and forth between me and Karin, but I felt hesitant to explain it in detail.

"Umm, I was just saying it's not realistic to draw fresh hot water every single day."

Karin might desire that, but with my thrifty nature, the first thing I think about is how much the water and gas bills would cost. I'm not even earning my own money, so I want to avoid unnecessary expenses.

...To begin with, since I practically live alone, I just take a shower every day, but at this point, some things are better left unsaid.

Chinatsu let out a small sigh and looked at Karin, speaking in an admonishing tone.

"I agree with that. Karin, will you just take a shower instead?"

"...Fine, I get it."

Perhaps seeing herself at a disadvantage, Karin yielded reluctantly. Resting her cheek on her hand on the table, she looked exactly like a pouting child.

Judging from this series of exchanges, Chinatsu seemed to be in a mother-like position for her four younger sisters. Her statements sounded more like those of a housewife with children rather than a high school girl.

"Other than that, we'll just decide things as problems or issues arise... Is that okay?"

"Yeah, sure."

"By the way, did you guys originally live as a three-generation household?"

Placing her pen on the table, Chinatsu stared intently at me. It was a natural question, but I slowly shook my head.

"No. It was just the three of us: me, Dad, and my mom who passed away."

"Hmm..."

Chinatsu looked puzzled, but I didn't feel like explaining any further.

It's a sprawling house that's a pain to clean, but if we're living with a large group, that works as a plus. Things might not go the same way as before, but Chinatsu and the others should be able to maintain their privacy and live comfortably enough.

When the discussion concluded smoothly, Karin, who had been quiet until then, spoke up.

"Hey, I'm thirsty."

Ah, I realized belatedly.

—Come to think of it, I haven't served anything on the table!

Someone else might have noticed too, but it was probably hard for the newcomers to this house to bring it up. I am truly inconsiderate.

"Mio, go get something."

Karin mercilessly treated her older sister like an errand boy. Normally you'd think it would be the other way around, but the timid-looking Mio didn't resist and stood up with a "Y-Yeah."

"Sorry. I'll do it. Is green tea okay?"

True to the prefecture praised as Japan's top tea-producing region, Shizuoka residents never run out of green tea. Even I always keep green tea stocked at all times. Around next week, the highly anticipated new tea season of Kawane tea will arrive.

As for tea snacks... I have none prepared. Yeah, let's not bring that up myself.

Returning from the dream world, Sorane raised her hand while rubbing one eye.

"Sorane wants orange juice."

"S-Sorry. We don't have juice. We have milk, though."

"I like milk too!"

"I see, that's good. Wait just a second, then."

Perhaps unable to watch me panicking, Chinatsu was about to stand up, but Mio offered before her.

"Umm, I-I'll help."

She really is a good girl, this kid...

"Thanks, that helps."

I nodded at Mio, and the two of us moved to the nearby kitchen.

"Could you take out enough glasses for everyone from that shelf?"

"Y-Yes."

I took out the pitcher with a tea strainer from the refrigerator. Cold green tea would be delicious today.

Mio lightly washed the glasses for me, so I poured the clear tea into them. While she carried the green tea on a tray, I prepared a glass of milk for Sorane.

"Here, thanks for waiting..."

And the moment I, holding the milk in one hand, was about to pass by Mio holding the empty tray.

The sole of my foot stepped on something that wasn't the floor.

"Ouch," I let out a stupid-sounding scream while losing my balance. I thought This is bad, but I couldn't brace myself. As I fell forward, the world looked like it was in slow motion to my eyes—.

"Kya!?"

A cute scream. And someone's voice calling Mio's name.

Thud! With a loud noise, I fell down hard.

"O-Oww..."

Grimacing at the strong impact, I opened my closed eyelids. Right then, my breath stopped.

Because between my two arms was Mio's body.

"...Eh..."

At point-blank range, our eyes met.

She probably still hadn't processed what was happening to her. On Mio's wide-eyed, frozen face and clothes, a massive amount of white liquid was splattered.

Needless to say, it was the milk I had spilled when I tripped. It trickled down the line of her beautiful jaw and spilled onto her chest.

...The color drained from my face.

In the back of my mind, Dad's smiling face flashed by like a kaleidoscope.

—'Just because I'm not around, don't go pushing Chinatsu and the others down.'

Even Dad wouldn't have dreamed of this. To think that such a joke would become a reality.

The white skin of the silent Mio flushed as if injected with vermilion.

Completely enveloped in the unique smell of milk instead of a sweet fragrance, she still looked so lovely and innocent that I, tormented by terrible guilt, broke into a sweat from every pore and let out something like a sob, "U-U-Umm."

It's no good. My head isn't working and I can't articulate my words. I have to apologize first. Then, if she's willing to listen, I need to explain that this was an accident...

"...I just had a thought."

The one who completely severed my spinning thoughts was Chinatsu's voice.

Even though absolutely no emotion could be read from it, a voice so chilling it gave me goosebumps rained down upon my head as I couldn't even look up.

"I wonder if a teenager with strong legs and a sturdy back would conveniently trip exactly when passing by a girl. And in that moment, end up splashing milk all over her... I wonder if such a thing happens in reality."

At least in my life up until now, it hasn't happened once, I thought, but I couldn't say it out loud. A slip of the tongue here would be a fatal wound. To me, of course.

"I'm sorry, but I won't listen to excuses. I don't intend to hear them, either."

A stinging tension ran down the nape of my neck.

"—!?"

The moment I pulled away from Mio as if jumping back, a flash of light crossed the left corner of my vision.

When I looked over in surprise, an expressionless Chinatsu was standing there. Crack, crackle, crackle! A sound like tiny consecutive lightning strikes echoed from her hands, and pale blue sparks scattered.

Having lived peacefully for these seventeen years, I never had the chance to see the real thing, but it was a self-defense item meant to protect oneself—a stun gun.

"Ugh."

Just as I thought Chinatsu closed the distance at once with that in hand, my head was slammed against the front of the kitchen. Fuka or someone let out a small scream, but I had no leeway to care about that.

—A wall slam.

I choked at the impact that couldn't be described with such a mild word.

Pressed firmly against my abdomen was the hard sensation of the stun gun. She had her finger on the switch on the side, but wasn't pressing it. However, if I made even a single mistake, Chinatsu's slender finger would undoubtedly press the switch without hesitation.

With my head and back pinned against the kitchen, my heart was beating deafeningly loud.

A single bead of sweat rolled down my cheek. Was she practicing some kind of martial arts? There was no opening whatsoever in Chinatsu's movements, and I didn't feel like I could escape.

Staying closely pressed against my body, Chinatsu crouched down with one knee raised and whispered dispassionately.

"Hmph. To be able to stay still without trembling in this state, you've got some nerve."

...I swallowed hard. Exposed to the burning, stinging bloodlust she emitted, the words wouldn't come out of my throat.

During that time, Mio was helped up by Karin and Sorane, and handed a towel by Fuka. But I couldn't even turn my eyes in that direction. Because from the bottom of my heart, I was overwhelmed by the person named Chinatsu.

It wasn't a facade put on because her parents were around. It wasn't the calm expressionlessness from a few minutes ago either. I learned that this bizarre and overwhelming intensity, something a high school girl shouldn't normally wear—a bloodlust like that of a wounded beast—was her true nature.

And yet, an impossibly sweet scent tickled my nose. Her soft hair brushed against my cheek. The contrast felt like it was going to fry my brain.

In the freezing air where no one twitched a muscle.

"—Let me give you one warning."

With dark eyes, Chinatsu readied the stun gun and continued in a low voice that chilled me to the marrow.

"Do not approach my sisters. Otherwise, you'll lose your life."

...This isn't a threat, I was certain.

This woman will do it. If she says she'll do it, she absolutely will. Forget a stun gun, she'd pull out a knife or whatever and mercilessly reap my life.

All of it, yes, for the sake of her beloved sisters.

"Even if our parents got married, we're complete strangers. There's no need for conversation or interference. At home, or at school, we will not get involved with you any more than necessary."

Spun from her colored lips was a declaration pregnant with anger. It probably wasn't just anger toward me for humiliating her sister. I felt like Chinatsu was indignant at and rebelling against something much bigger.

"Well, do you understand? If you understand, nod without saying anything."

It seemed Chinatsu also had an impatient nature. Poke, prod, push, the tip of the stun gun was pressed forcefully into my stomach.

Unable to bear it, I broke out in a cold sweat all over my body while nodding my head up and down repeatedly.

Confirming that reaction, Chinatsu finally let go. She quickly stood up and rushed over to Mio with a worried look.

"Mio, are you okay? Let's just have you take a bath for now."

While gently placing a hand on her sister's back, she called out to the other sisters in a bright voice.

"Everyone else, let's start unpacking soon!"

She gave off no hint of anger, bloodlust, or even the lingering scent of it. Her dependable profile, like a portrait titled "Older Sister," disappeared from my vision.

In the living room, completely enveloped in silence with no one else left, I stared up at the ceiling, remaining powerlessly leaned against the kitchen.

That was my encounter with Chinatsu—the terrifying stun-gun woman, Chinatsu Miyanaga.

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