When I Comforted My Sickly Stepsister, She Couldn’t Live Without Me

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“Whoa, nice one, Yukine.”

“Ni-Nii-san, too”

Facing the TV screen, we’re both intensely focused on manipulating our controllers. Yukine sits beside me, keeping a distance of about one person’s width, just as engrossed in the screen as I am.

It’s currently eleven at night. After dinner, I knocked on Yukine’s room door somewhat impulsively, and here we are now.

“(It’s become so natural for her to let me into her room.)”

“Opening!”

“Huh?! W-When did you do that?!”

While I was admiring Yukine’s progress, my character was thrown off-screen. I’ve lost, having turned into Zero HP.

Ignoring Yukine’s slight look of satisfaction, I stretched.

“You’re really good at this, Yukine.”

“N-No, I’m not. You just let your guard down, Nii-san.”

“Well… yeah, that’s true. But still, Yukine, you’re good at the game.”

“T-That’s… well, that’s just…”

Yukine blushed and pouted embarrassedly. Compared to the beginning, she has become much more relaxed around me.

Satisfied with that, Yukine put her controller on the desk.

“Nii-san, I… I’m going to go take a bath.”

“Oh, right.”

Come to think of it, it’s about that time. We both have school tomorrow, and even though she doesn’t go out much, Yukine attends a correspondence high school, so staying up too late isn’t a good idea.

“Hey, Yukine.”

“W-What?”

“…Want to join me?”

“Huh?! W-What are you…!”

Yukine, her face turning bright red, covered her face with both hands while fidgeting. What a reaction. It’s incredibly cute.

Feeling mischievous, I grinned teasingly.

“We’re siblings, so it wouldn’t be weird to take a bath together, right?”

“T-That’s…”

“Also, it’s not a bad idea to strengthen our bond by washing each other’s backs.”

“…”

Oops, I teased her too much, and Yukine fell silent.

Realizing I went overboard, I decided to stop.

“Just kidding, just kidding. It would definitely be weird for siblings our age to bathe together.”

“Y-Yeah…”

“Sorry sorry.”

“…….Nii-san meanie.”

Yukine pouted and turned her head away. Even that is cute to me. Am I what they call a siscon?

It’s only been about two months since Yukine became my little sister.

“Jeez…”

…No, she’s still cute. The cutest in the universe.

Yeah, my little sister is the cutest in the entire universe.

“――I wonder if I’m sick or something.”

“It’s an incurable disease. With modern medical technology, it’s impossible to cure.”

“Seriously?”

Drooping weakly over the desk, I’m met with a sigh of exasperation from a seemingly serious girl.

“Really, Miyoshi-kun, you’re really into your little sister, huh?”

With a slight smile, my classmate, Mari Imari, said this.

Imari stands out with her glossy, long black hair, and when it comes to cuteness or beauty, she leans heavily toward beauty. But above all—her chest is large.

There’s no one in the same grade as Imari who can rival her, and she boasts the most spectacular chest size in the school, if not the entire district.

By the way, what makes it so spectacular? Well, not just the size, but also the shape, firmness, and the strong presence even through her uniform are all factors.

Setting aside the topic of her chest… Imari always ranks first in tests, has a good personality, and is well-liked by everyone, so she serves as the class representative.

We’ve been in the same class from our first year to our third year, so we’ve known each other for quite a while.

To put it plainly, she’s the friend I trust the most.

“Well, of course. After all, I’ve always wanted a sibling, and suddenly having a cute sister close to my age…”

“Cute, huh? Is she really that cute?”

“She’s unbelievably cute. She’s cute beyond anything I’ve ever seen. Honestly, I think she could easily conquer the world.”

“Is Miyoshi-kun’s sister some kind of world conqueror?”

“That would depend on Yukine’s whims.”

“That would be an amazing sister.”

Imari chuckled softly.

“But seriously, you can’t fall in love with her, okay? No matter how cute she is, she’s still your sister.”

“Of course. I want to be Yukine’s family, not her boyfriend.”

“Then let me ask you this, what will you do if she gets a boyfriend?”

“For starters, I’ll kill him.”

“Just ‘for starters’…?”

“After that, I’ll kill him again.”

“Love and hate really do go hand in hand…”

I don’t want to imagine Yukine with a boyfriend. It’s only been two months since I became her big brother, but my big brother spirit towards Yukine has already reached that point.

…I see, so I’m apparently a siscon. Well, that’s okay, it’s not a crime.

(Tl/n: committing a crime is though)

“Well, as long as Miyoshi-kun doesn’t commit any crimes, I’m fine with it. It would be a rude awakening to find out my friend is a criminal.”

“Don’t worry about that. As you know, Imari, I’m quite the sensible guy.”

“I don’t think many people would say that about themselves… Well, I’ve spent three years with you, so I know.”

“That’s my Imari-san for you.”

“I have no recollection of becoming yours, though.”

As she threw out a light jab, the bell rang, and our homeroom teacher entered the classroom.

“Well, someday let me meet your beloved little sister.”

Imari stood up and said that before returning to her seat.

I stole a glance at Imari, who walked confidently back to her seat, trying not to get caught.

“(…Yeah, her chest really is something. It might be the best in the universe.)”