What I could do for my little sister was take care of her while I was home. It sounded like a stupid tautology, but that was the truth, so there was no helping it.

Tomorrow, I was going out with Yuu, and I was going to be out almost the whole day.

Was it really okay for me to leave the house for an entire day?

I didn’t have an answer to that myself.

From a safety standpoint, even leaving the house during the day carried risks, but if I took that logic to the extreme, then I wouldn’t even be able to go to school. While I was at school, while I was living out something that could pass for a normal student life, my sister still got through her days without any real trouble, holed up in the house like always.

So going to school, and even the delay from shopping for daily necessities before or after that, still fell within the bounds of our usual routine.

More specifically, in my current life, the amount of time I could leave the house without it being a problem came out to roughly twelve hours, from eight in the morning to eight at night. But that only applied on weekdays.

On days when school was off, that so-called free time actually tended to shrink precisely because school was off.

Our parents came home once in a while, but they never stayed long. A few days at most, and sometimes just one or two. The gap between one visit and the next was usually at least a month.

That meant our parents were gone, my sister stayed shut inside, and that situation could go on for over a month at a time. In that kind of setup, if there wasn’t something more important demanding my attention, then all I could do was focus on the top priority: protecting my sister and protecting this house.

School. Shopping. Those were the only two excuses that freed me from house guard duty.

If those excuses didn’t hold, then the responsibility for my sister’s safety and the safety of this house fell squarely on me. I couldn’t stay out all night screwing around at karaoke, and I couldn’t even bring a male friend into the house just because he was a friend.

Ever since middle school, and even now that I was in high school, I’d done what I could to manage security with the limited authority I had. But how long could I keep this up? Could I even keep it up at all?

If I’m being honest, I’d feel a hell of a lot better if we lived in a place with an auto-locking front door, something like Liar-chan’s house, but that wasn’t happening.

Assets were finite, and once a house was built, it didn’t change unless you rebuilt it or renovated it. I was still a minor, and I sure as hell wasn’t a carpenter. If I couldn’t change the house, then the only thing left to change was my life.

The truth was, this life came with way more restrictions than most people would guess.

“Legal emancipation through marriage... yeah, that’s not very realistic.”

In legal terms, when a minor got married, they were treated like an adult. It came with all kinds of obligations, but it also increased the number of things they could do on their own. If I used that, if I got someone to enter a paper-only marriage with me, then maybe this life too—

“...No. That won’t work. My sister’s living situation probably wouldn’t change at all. If she doesn’t walk out of that sealed room on her own, then none of it matters. Even if I resort to some special trick, all it’ll do is waste money, time, and effort, and in the end it’ll just turn into another shackle...”

Only a tiny handful of people ever got real benefits from those kinds of special measures. Adoption wouldn’t work either, for pretty much the same reason. On top of that, our parents would almost definitely never approve it.

“...What’s going to happen to this house after I graduate high school?”

I thought about that vaguely. Some relatives had disappeared on us. I’d also been passed around between the few relatives whose whereabouts we did know.

In the end, there was no one I could rely on to take care of us, and this was the life I ended up with. Blood was thinner than water.

Who the hell am I even supposed to rely on?

The Onodera family next door? Sure, if I asked, they’d definitely help. They’d probably wear themselves down doing it, too. Yuu had already proven how dependable she was.

Thankfully, she’d been helping with part of my daily life already, mostly the food side of things. But I’d decided not to use her. Not her family either. There was no point in it.

No, that wording wasn’t right. In my current situation, if I borrowed their strength, it wouldn’t even count as using them in the sense of making good use of someone’s abilities. It would just be leaning on them, plain and simple.

Either way, I’d already decided I wasn’t going to use Yuu or her family, and the biggest reason for that was probably emotional more than anything else.

Even though Yuu stayed by my side, I hadn’t been able to give her anything back. I wanted to, but in the end I kept relying on her.

Was that really what happiness looked like for her? Yuu would probably still smile and say yes. But that happiness would only be temporary.

Someday, I had a feeling I’d become the one who pulled the trigger and put an end to myself. If Yuu ever saw that moment, then I’d be making her miserable too.

“...Seriously, what the hell is going to happen to us?”

What about my shut-in sister? What about our parents, who were so busy they could barely stay home? What about my future? And what about hers?

I didn’t know. I didn’t know a damn thing. My future had always been a blank sheet ripped to pieces.

No... screw that. Enough with the negative crap. I had to think positively. If I wanted to put it another way, then my future, the one I still hadn’t seen yet, was always blank because it was full of possibilities.

Think optimistically. Think about something fun.

I came back to myself in the first-floor living room. I must’ve zoned out for a while. My stomach growled.

“Come to think of it, I haven’t eaten anything. Guess I should make dinner for myself too—”

As usual, I’d forgotten to make my own meal, and the seafood-flavored cup noodles I’d bought by the box and turned into a ridiculous excess stockpile flashed through my mind.

“...Yeah, no. I don’t want it.”

I was completely sick of them. Seriously, forgive me, but there was no way in hell I was finishing all of those before they expired. Absolutely no way.

“Yeah, screw it. I’ll just study instead.”

With no better option, I opened my school bag and spread out my study materials. Pens, textbooks, notebooks, reference books. Even when I tried to keep it compact, they still took up more than half the table.

I studied in silence like that, and by the time I finished reviewing two subjects’ worth of material for the next test, I finally closed the reference book.

When I looked at the clock, it was around eleven at night. About two and a half hours had passed.

“I’m tired.”

I was tired, but...

“...I’m not getting sleepy.”

I should’ve been exhausted. I should’ve been sleepy. But somehow I was sure I wouldn’t be able to sleep like this. I knew the feeling.

My body had already memorized that rotten, familiar sensation of insomnia from being tormented by it more times than I could count.

Being sleepy and still not being able to sleep was a weird feeling, and not in a good way. Your thinking slowed down, so you spent more time spacing out. Everything you did got less efficient.

The cause was lack of sleep, but you still couldn’t sleep, and while working in that sluggish state you spaced out even more, which only made everything worse. It was a full-on negative loop. A vicious cycle.

“...Did I overthink too much earlier?”

Yeah. That was probably exactly it.

Once everything started feeling pointless, I decided to take a shower without even bothering to put my study materials away.

When I opened my eyes again, they’d adjusted to the darkness enough that I could faintly make out the outlines of things, and I could tell a good amount of time had passed without me ever actually falling asleep.

After getting out of the bath, I’d sunk into the sofa, shut my eyes, and just stayed there. How many minutes had gone by? I grabbed the remote and turned on the little night light in the living room ceiling fixture, and the clock in the dim room told me the answer.

Only about ten minutes.

...You’ve got to be kidding me.

The faint hope I’d had before trying to sleep had been crushed just like that. Hardly any time had passed. I’d tried not to think about anything, but I still hadn’t slept.

My head hadn’t rested at all. My body, maybe. I could feel the physical fatigue easing little by little.

“...Shit.”

Lately, I’d been spending more time with Yuu, and for some reason my sleep quality had gotten better. It had felt like some weird miracle.

But apparently that was all it was. A miracle. Without the blessing of that girl named Yuu, that angel, I apparently couldn’t even sleep properly.

That made it sound like I was starting to depend on Yuu.

“...!”

I was depending on Yuu? Using her? Leaning on her? For someone who absolutely could not allow that, it was the kind of reality that sent a cold chill straight down my spine.

Taking advantage of her kindness, of her goodwill, would mean crossing the absolute lowest line I’d drawn for myself.

“Me...?”

No. This was bad. Sleep deprivation was bad.

“I... ah, right. If I’m going to sleep, I need to go to bed...”

Obviously. Maybe my brain was so fried it had started treating anything I could rest against like a bed. If that was the case, then maybe I really was craving sleep on an unconscious level.

Then just bring the damn sleep already!

Anyway, I got off the sofa and headed upstairs on unsteady legs. A few times on the stairs, I nearly missed my footing. My vision was shaking. I somehow managed to reach the top.

Then it happened.

A creak.

“—!”

Somewhere in the hallway, or maybe in one of the rooms, I heard the floorboards groan.

“...Huh?”

Had my sister come out of her room? No. There was no way. It was such a faint hope, the kind I already knew would betray me. There was no way that had happened.

Sure enough, the door at the very back of the hall, the sealed room that never opened, was still shut tight. And if I thought about it calmly, there was no way the sound of the floor in her room would carry all the way to the stairs.

“Is someone there...?”

There was no shadow in the hallway. Still, the sound from earlier couldn’t have come from very far away.

It also wasn’t like this house was some ancient wooden wreck where me walking up the stairs would somehow make part of the upstairs hallway creak.

Without a word, I looked at the closest door from where I stood.

My room.

“Is someone in there?”

Of course, there was no answer.

I stepped in front of my door and opened it without hesitation.

“Who’s there?”

Nothing.

The room was pitch black, but my eyes were used to the dark enough to make out the desk, the chair, and the bed. The window wasn’t open. There wasn’t any suspicious figure in there.

“...Maybe I’m just being too damn jumpy.”

Tomorrow, I was planning to leave the house longer than usual because of my date with Yuu. Maybe that fear had sunk into me deeper than I realized, making me too alert.

If some creep ever got into the house and hurt my sister while I was gone, I’d regret it for the rest of my life.

If only I’d been home. If only I could’ve stayed by her side.

“…Well, as long as it’s not an intruder… that’s a relief.”

I let out a genuine sigh from the bottom of my heart and stepped inside, flicking on the light.

“…Huh?”

The moment I entered the room, something felt off.

Even with the light on, a heavy wave of drowsiness crashed over me out of nowhere. I hadn’t been able to sleep at all in complete darkness, and yet now—

“…Why do I feel so calm?”

It was strange. Some kind of warmth seemed to wrap itself around my body. I switched the light back off, staggered toward the bed under the weight of that sudden exhaustion, and collapsed onto it.

It was later than usual, but for some reason, I felt like I could finally sleep properly tonight.

I thought I felt something soft brush against me, but the comfort of that warmth completely lowered my guard. My thoughts blurred almost instantly, and I sank straight into sleep.

A feverish voice brushed against me at close range like a whisper.

Warm breath touched the side of my neck.

Yuu was clinging tightly to me, breathing unevenly as if she couldn’t bear to let go.

She kept pressing closer, burying herself against me, taking in my scent while holding onto me with an intensity that didn’t match the Yuu I knew at all.

She was my childhood friend. My next-door neighbor. The girl pretending to date me. The school’s golden girl. An honors student.

And yet, in this dream, her long black hair had been let down instead of tied into her usual braid. Her loungewear was slightly disheveled as she clung to me with a reckless, unfamiliar need.

Anyone who knew her would’ve thought this side of her was impossible.

Then I understood...

A lucid dream.

One of those dreams where you realize you’re dreaming while it’s happening.

That was exactly what this was.

Right now, I was dreaming.

The setting was my room. In the darkness, Yuu lay beside me, wrapped around me, breathing softly against my neck while pressing herself tightly against my body.

The warmth trapped beneath the blanket, the faint scent of soap lingering after her bath, the overwhelming sense of her presence filling the room—

All of it wrapped around me with a strangely gentle comfort.

And the strangest part was that none of it felt unpleasant.

That was when the version of me inside the dream understood it instinctively.

So that was the reason.

This was why I’d been sleeping so well lately.

Yuu’s presence lingering in the room. Her warmth. Her scent. The traces she left behind.

All of it had been pulling me down into a deep, muddy sleep filled with unbearable comfort and relief.

There was no way that should’ve made sense.

It was ridiculous.

And yet… that was honestly what I thought.

Chapter 10: I Went on a Date with a Beautiful Girl, and Somehow We Ended Up Crossing the Line Together