That Time My Sex-Friend Became My Step-Sister - Chapter 3
Chapter 3
We left the house and arrived at a large shopping complex nearby. The movie theater we’re going to tomorrow is in this complex too. Since it’s summer break, even though it’s a weekday afternoon, the place is packed with young people.
There are several clothing stores inside, but we already know where we’re headed. We’re high school students, so we can only shop at cheap places. I checked the directory for the shop’s location and took the elevator to the second floor.
“Hey, do you think people see us as a couple?”
“We’re not even holding hands. I doubt it.”
“Then, should we hold hands?”
“Why the hell would we? If someone we know saw us like that, we’d be screwed.”
I brushed off Yuina’s joke and stood in front of the store. To be honest, I’m not used to shopping for clothes. I usually wear the same stuff for a long time and don’t have much variety to begin with. Clothes are expensive, especially on a high schooler’s allowance, so I’ve never really asked my dad to buy me any. I’ve never been that into clothes anyway. That’s why stepping into a clothing store takes a bit of courage—but at least Yuina’s with me today.
She seems used to shopping and probably won’t attract the attention of any store clerks.
“So, what kind of clothes are you gonna get?”
“What do you think I should get?”
“Seriously? You’re just dumping it all on me? Well, fine. But if you’re walking next to me, no way I’m letting you dress like a dork.”
With that, Yuina grabbed my hand and led me toward the men’s section. She picked up a shirt and immediately held it up against me.
“Yup, that looks good. Simple styles like this are best.”
It was a plain shirt with no illustrations or logos. She picked up a few more like it and held them up against me one by one.
“Hmm, this one might work too. Which do you like, Hotaka?”
“If it’s simple, I don’t really care. But are clothes like this really okay for a date?”
“You don’t get it at all, Hotaka. For a date, as long as you look clean and presentable, that’s all it takes to come off as stylish.”
Is that how it works? I’ve never been on a date, so I wouldn’t know. I imagined something flashier.
“Guys who suddenly go over the top just because it’s a date? Big mistake. Trust me—it backfires.”
If a girl’s saying it, she’s probably right. I imagined exactly the kind of flashy outfit she just warned me against. I felt a little embarrassed.
After carefully inspecting the shirts, Yuina handed me one.
“I think this one’s the best. It suits your calm vibe.”
“Alright, I’ll go with that.”
With the shirt decided, we moved on to look for a jacket. Yuina picked one up and held it to me.
“This one goes well with the shirt.”
“Nice. I’ll take that too.”
Lastly, we looked for pants. To match the top, Yuina picked out a pair of beige chinos. We took everything to the register, and the total came out under ten thousand yen. Yuina had chosen well, keeping an eye on the price. Bringing her along was definitely the right call. Having the girl-you’re-going-on-a-date-with help choose your outfit can no way you can go wrong.
“Man, choosing clothes for a date is rough. I usually just go for whatever’s comfortable.”
When I said that, Yuina raised her index finger and said:
“What are you talking about? Date outfits are super important. Pick the right clothes and even an ugly guy can look like a hottie.”
Coming from someone like Yuina, who clearly pays attention to fashion, it carried serious weight.
“Oh! Since we’re here, you should pick out an outfit for me too.”
“Huh? Do you know how intimidating that is for a guy?”
“Just pick what you want me to wear. I picked yours, so it’s only fair.”
Hard to argue with that. But I really suck at this kind of thing. What kind of criteria am I even supposed to use to choose girls’ clothes? Before I could figure it out, Yuina dragged me over to the women’s section with zero hesitation.
I steeled myself and looked at the clothes. Yuina often wears tops with low necklines, but if I pick something too revealing, I’ll only be enabling her teasing. I should aim for something more modest.
First, I picked a white T-shirt with a small logo. Then I chose a black dress and handed them to Yuina.
“Here.”
“Got it. I’ll try them on, so give me your thoughts.”
She disappeared into the fitting room. After a short wait, the curtain opened and Yuina stepped out.
“Whoa…”
At first glance, she looked innocent—just like I intended. But with her figure, even this outfit hinted at a hidden eroticness that could melt a guy’s brain. The subtle mature allure she gave off in that outfit made me gulp. This is bad. Being around her in that will make me want to strip her down.
“Can I pick another one too, just in case?”
I returned to the racks. I didn’t expect my ‘safe’ choice to backfire like that. But I couldn’t go for something more revealing either—that would only expose my own desires.
After some careful searching, I chose a shirt dress and a cardigan. That should downplay her chest. I brought them back to the fitting room.
“Try this one too.”
“Okay.”
She disappeared behind the curtain again. I could hear the rustling of clothes. Just listening to it made me nervous. When she stepped out, I held my breath.
“…This is…”
Cute. That was my honest first thought. The shirt dress was short enough to show off her bare legs, which were pretty damn distracting—but at least it felt more like a typical high school girl’s outfit. Compared to the last one, this was something I could actually walk next to her in.
“I think this one’s better.”
“Oh? So you’re into bare legs, huh? Honestly, I expected you to pick something with more cleavage.”
No way I was telling her the reason I didn’t do that. But seriously, everything looks good on her. She’s got the kind of figure other girls would kill for.
“Alright, I’ll go buy this one then.”
Yuina headed to the register. I waited outside the store and let out a breath. Mission complete. I’d managed the impossible task of buying clothes for a date. That unexpected detour where I had to choose Yuina’s outfit was tough, but I survived. She seemed happy with my choice too—guess I passed. I mean, she’s actually going to wear what I picked. That’s kinda exciting. Maybe that was her plan all along.
“Thanks for waiting.”
Yuina returned. Since we’d finished our shopping, it was time to head home or so I thought. But then she tugged at my sleeve.
“Hey, let’s go to the arcade.”
Yuina dragged me to the arcade.
“Let’s take a purikura.”
“Why?”
“Hmm… to celebrate becoming family.”
“…Fine.”
At her insistence, we moved to the purikura booth. I’d never done this before, so I had no idea how it worked. I let Yuina pick the machine and just followed her lead into the booth. A cute voice told us how to pose—make a heart with our hands, pretend to have cat ears… apparently you don’t get to pose freely. Yuina was really into it. I felt incredibly self-conscious, but with her egging me on, I did the poses too.
After the photos, there was a “decorating” time. I had no idea what to draw, but Yuina happily started doodling. There were tons of stamps to choose from. I just slapped a few on at random. Curious about what she was writing, I peeked over—and saw her write “Sex-friend.”
“Hey! You can’t write that!”
“Why not? It’s not like we’re showing it to anyone.”
“Still! And besides, we’re not sex-friends anymore.”
“I still think we are.”
But she must’ve been joking, because she erased it right after. Just teasing me again, probably. When we finished decorating, it was time to print. Before that, we scanned a QR code and each selected a picture to transfer to our phones.
“Man, our eyes are huge. It’s freaky.”
“Both of us already have big eyes, so now they’re just… massive.”
We split the printed photos.
“Here—sibling commemoration.”
“If it’s for that, then sure. I’ll keep it.”
I slipped the photo into my notebook. Yuina smiled and grabbed my hand again.
“Let’s do the claw machine next!”
We moved to a crane game so Yuina could get a stuffed animal. I’m actually pretty good at this stuff. I don’t usually bother since I don’t want the prizes, but whenever I really want something, I always get it. I aimed for a cat plush Yuina wanted. Since the claw was weak, I had to be strategic—threaded the arm through the strap and lifted it. The plush rose smoothly and landed in the prize chute. Yuina clapped and cheered.
“Whoa! That’s amazing! How’d you do that?!”
“I’m just decent at it.”
“You could win anything!”
“Better not. They’ll ban me.”
I kept her content with the cat plush and we played around the arcade a bit more before heading home. I probably spent too much, considering we’re going out again tomorrow. But Yuina had fun, so I guess it’s fine. On the way home, she suggested taking a detour, and I followed along.
Eventually, we ended up in a familiar love hotel district.
“Hey…”
“What’s wrong? Wanna take a break?”
She said it in a teasing tone, clearly expecting something.
“No way. Why’d you even bring me here?”
“Oh, we just happened to pass through while taking the detour.”
Yeah, right. She gave a fake laugh while averting her eyes.
“You little slut.”
“Rude. I’ve only ever done it with you.”
I still wasn’t sure if that was true, but I was her first—so maybe it wasn’t a lie.
“I don’t just like doing it. I like doing it with you, Hotaka.”
Yuina said that with her hand over her heart.
Even if she says that… we’re family now. Having a sexual relationship as siblings is just wrong. Dad and Ms. Yuni would be devastated if they found out. That’s why—I can’t sleep with Yuina anymore.





































