My stepmother's burden is my ex-girlfriend.

"But...but I didn't bring any clothes to change into..."

"Ah, right. If I go out to get my clothes... oh dear! I'll just have to hide! Let me see—I've got it!"

"Ooh!"

The sink pushed me to the floor and lifted the entire seat of the sofa. It turned out to be a model with storage space.

"Okay, go in! Hurry up!"

"Wait, wait a minute! Don't push me like that, I can do it myself...! Ouch! You kicked me! You just kicked me, didn't you!"

"Don't speak, understand?"

After the sink tucked me into the storage space inside the sofa, it covered the seat.

My vision went completely dark.

"—Huh? Mizuto, you're all alone?"

"I think I heard Yume's voice..."

"You're back, Dad, Aunt Yu-ren. Yui-na is asleep now—"

Hearing Shuidou lying to his mother and the others, I couldn't help but think of what had just happened.

Just now... if Mom and the others hadn't come back...

What...did I just do...?

"...Waaaaaah...!"

That's so strange. That's really strange!

We've broken up. I hate him now. He's become an annoying stepbrother who makes me angry no matter what he does, not a boyfriend at all! But I... I...!

I pressed my hand against my wildly pounding heart.

Why is everything always going so wrong?

It was so hard to end that relationship—it was so hard to finally be free.

I became his brother and sister, and even seduced him. Only now do I realize that we are two of a kind!

"...Ugh, that's enough...!"

I just hate places like yours!

◆

The next day, I exercised the rights of the winner.

"You said it was okay to pretend you lost, right, Mizuto-kun?"

"...Okay, I did say that. But I guess you forced me to say it—"

"That's how it is, little brother. This is your older sister's order: leave the room for a moment."

After I chased Shuidou out of his room, I began searching the house.

Yesterday, Shuidou said, "When you asked me to come to your house a year ago, you were fully prepared"... If that's the case, it means that thing definitely exists. If we can't find it, so be it, but if the thing is still there, we absolutely have to get rid of it.

I originally planned to search everything from under the bed to behind the bookshelf, but I found what I was looking for as soon as I started looking through the drawers, which made me feel a little disappointed... But given that man's personality, he certainly wouldn't use some inexplicable and laborious way to hide things.

I took what I found and left the water well's room.

Shuidou, who was waiting in the corridor, looked at me with the same eyes that of a dead fish left to rot.

"What exactly are you looking for?"

Where is 'Sister'?

"...Older sister."

"I'm looking for something my step-siblings don't need."

I hid the small box, which said it was a dozen (twelve pieces) on the packaging, behind my back and said nonchalantly, "Buying a dozen? Is that an unexpected burst of energy?" Uh—well… I just happened to buy a dozen, right? There's no rule that you have to use them all at once, right? I guess so.

As I brushed past Shui Dou, I made sure he didn't see me, and headed towards the stairs leading to the first floor.

"Hey, sis."

An rude voice called me from behind, and I just turned around to look at him.

"What is it, my little brother, Mizuto?"

"So-called step-siblings—"

He looked away halfway through his sentence and gave a vague answer.

"Never mind, it's nothing."

I snorted and walked down the stairs.

I walked to the trash bag in the entryway, threw the small box inside, and tied the bag tightly to prevent any leaks.

Then, all we have to do is take it out and throw it away on the day we take out the trash, and that's it. This way, the mistakes that siblings shouldn't make will never have a chance to happen.

I took a breath, looked at the front door... and then looked back up the stairs.

Even knowing he couldn't hear me, I still answered:

"...Of course I know that much common sense."

However, this little bit of common sense is completely useless. Am I wrong? Memorizing this kind of common sense is pointless. Knowing it is of no productive use... and it's utterly meaningless to say it aloud.

So he didn't say it.

Therefore, I will not say it out loud.

To mention something as trivial as the fact that step-siblings can marry.

Volume 1: Past Romance Lingers - Couples Prepare for School Start - "Aren't you lonely?"

Looking back, I can only say it was a mistake I made when I was young. However, I did have what is commonly known as a girlfriend between my second and third years of junior high school.

Everyone has a past, and that makes sense. Even a brooding, hard-hearted person like me, who looks back on the past with a melancholy attitude, had a naive and ignorant youth.

For example, the first day of the second semester of the second year of junior high school.

That day, with unusually sleepy eyes, I slowly got out of bed—for me now, explaining the reason for my lack of sleep would make me regret it deeply, and even for me back then it would have been extremely shameful. However, if I were to explain it with shame and humiliation, the reason stemmed from what happened the day before.

Ayai Yume confessed her feelings to me.

I read the love letter she handed me on the spot and replied immediately—or rather, perhaps "accidentally replied"—but in any case, from the day before, I officially became someone with a girlfriend.

My first girlfriend in this life.

Even if one's mood becomes a little restless or a little excited, and one tosses and turns in bed until dawn without any particular reason, it's quite natural—it's not because I feel reality is better than dreams and therefore don't want to enter a real sleep state. It's simply due to the influence of natural physiological phenomena, resulting in the loss of precious sleep time. Ayai is truly unforgivable.

In short, that was my first morning after I got a girlfriend.

And it was a one-time event, the only first morning of the second semester of the second year of junior high school.

I quickly finished washing up and rushed out of the house.

It's not because I think being late for the entrance ceremony is a bad thing. It's because I have an appointment with someone.

At the intersection on my way to school, which would later become the location of my first kiss, a petite girl with braids was waiting for me, her schoolbag held in front of her knees.

Yui Ayai.

That's my girlfriend.

--I'm so sorry! I overslept...!

--It's okay...I won't be late...

Back then, Ayai was quite clumsy when speaking, and she would even stutter when talking to me. I really don't understand how that mouth later turned into that hateful, foul-mouthed one that spews venom. It makes me angry just thinking about it, but let's put that question aside for now.

Ayai glanced at my face furtively, then gave a slight smile.

--Could it be... that you didn't sleep well yesterday?

--Uh, um...yes, a little...um.

--I see...

While playing with her long bangs with her fingers, Ayai subtly averted her gaze, her cheeks flushing slightly, and murmured in a voice so soft it seemed as if it would be blown away by the wind:

—Me too… Yesterday, I couldn’t sleep at all…

After all, I was incredibly foolish back then, and this conversation completely captivated me. My heart was pounding, and my tongue became five times clumsy than Ayai's, like a robot that hadn't been oiled.

We walked side by side to school, chatting idly about trivial things. We were only about half a step apart, so close that the backs of our hands almost touched as we walked.

Now that we're a couple, maybe I can hold her hand.

But I only confessed my feelings yesterday, so maybe this is too hasty.

In short, these things were on my mind, but for a stupid virgin like me who cherished even the slightest touch of fingertips until the day before, holding hands was just too difficult.

When I came to my senses, I realized that the school was already fifty meters away in front of me.

And I also started to see some other scattered students on their way to school. Just as I was feeling reluctant to leave and thinking, "Ah, it's already over so soon—hahaha, I think your life should be over by now—", Ayai started sneaking around looking around furtively.

Ah... could it be... right here...?

--Huh?

—Let's go into the classroom together... I...I'll be shy...

Hearing Ayai say that in an almost inaudible voice, I was momentarily taken aback and found her incredibly cute. This sealed my fate—from that moment on, my relationship with Ayai became an unspeakable secret.

If we had walked into the classroom together openly and proudly at that moment, and grandly announced that we had started dating, perhaps I wouldn't have had to argue because of my strange possessiveness, and Ayai wouldn't have been unreasonable with me—furthermore, perhaps we wouldn't have broken up.

It's too late to regret.

We are neither Kazuko Yoshiyama nor Subaru Natsuki, so any fantasies about "what ifs" are just playing a game of imagination—but yes, so let's treat it as a game of imagination, let me say something.

If, assuming...

What if Ayai and I had walked into the school together that day?

Even a hardliner like me never expected that this "IF" would actually come to pass.

◆

The most hateful period of my life—spring break before starting high school—is finally coming to an end.

While this event itself is worthy of genuine celebration, a completely new and enormous problem stands in my way.

"........."

"........."

Whenever I encountered my stepsister, Yui Irito, who appeared from the restroom, I would stare at her without saying a word.

What we were staring at with furrowed brows, or more accurately, at the uniforms worn by both sides, was their uniforms.

The uniform features a dark blue suit jacket, designed in a conservative style that gives a false impression of seriousness. Red ties or ribbons are symbols of first-year students.

Yui and I were wearing the uniforms of the same high school.

Speaking of this, I can't help but mention another tragic trap set by God, second only to the fact that I became siblings with this woman.

Last year, when students officially began preparing for high school entrance exams—my relationship with Jienu had already reached a stalemate.

Of course, we didn't discuss how to fill out the college application forms at all. On the contrary, to avoid going to the same high school as her, I put our prestigious private school, which had never had any students getting into our junior high school, as my first choice.

Although I, coming from a single-parent family, also had to worry about tuition fees, this would be solved as long as I passed the special entrance exam—I heard that this girl was also from a single-parent family, and I was convinced that as long as I got into this high school, I would never meet her again, so I studied hard to prepare for the exam.

Then I succeeded and obtained the special treatment student qualification.

Together with Yui.

...that's right.

This woman and I have the exact same idea.

She was determined not to go to the same high school as me, so she chose a high school that I would never attend as her choice and studied hard to prepare for the exam.

As a result, the remarkable feat of having two rare special admission slots occupied by the same junior high school was achieved.

When we were both called to the faculty office and praised as "the pride of our school!", can you understand the despair I felt? To be honest, it was a bigger blow than failing the exam. The blow was so great that I could only keep putting on a forced smile.

There are many couples in the world who study hard because they want to attend the same school, but we are definitely the only couple who study hard with the intention of never wanting to attend the same school—and in the end, we still end up attending the same high school. Now we're even rarer.

Damn God.