Daily Life with My Little Sister!!

It's been a month since Miyu became part of our family. 

Miyu was able to enroll in the same middle school I attend, and she's in the same grade as me.

While keeping the other world a secret from the school, we explained that Miyu had no relatives and that we had taken her in as our adopted daughter. They seemed to believe us, and she was able to start school without any issues. 

By the way, she hasn't actually attended class yet. 

The reason? It's August, and it's summer break. 

So, she'll start attending classes with everyone else after the break. 

Honestly, I'm glad it's summer break. 

If it weren't, I'd probably be bombarded with questions about the changes in my body. 

At worst, I could've used feeling unwell as an excuse to skip school, but… 

"Big bro, that X is squared." 

"Huh? Seriously?" 

Right now, Miyu and I are studying for our upcoming exams. 

Since Miyu hasn't been in this world for long, I thought studying for the exams would be tough for her, but she's already mastered almost all of the middle school material in less than a month. 

Now, she's better at studying than I am and can even teach me. 

Ugh… I feel so pathetic… 

"Still, Miyu, you're really smart. How did you study? Do you have some secret trick?" 

"There's no secret trick. I just studied normally." 

No, no, that's not normal! 

How can you master three years' worth of material in a month!? 

Was middle school material always this easy!? 

Or is my head just that bad!? 

Damn, is this what it feels like to be surpassed by your little sister…? 

"D-don't be so down, big bro! You're just a little weak at studying, but you're better than anyone at everything else!" 

As I sink into despair, Miyu comforts me. 

By the way, being called "big bro" by Miyu really hits me in the feels. 

I have a siscon acquaintance, and I think I understand his feelings a little now. 

Just being called "big bro" by Miyu gives me so much energy! 

It makes me feel happy! 

"Thanks. I'll do my best too!" 

"Yeah! Let's do our best together!" 

After a while, today's study session (though I was mostly being taught by Miyu…) ended, so I stretched my back. 

I exhaled and rolled my neck. 

"I'm tired…" 

Today, we focused on math, but it's been three years since I last studied math. 

When you haven't done it in a while, even the basics slip away, so I struggled with simple problems. 

…Well, Miyu, who's seeing it for the first time, has already mastered it. 

Still, I've been remembering a lot over the past month. 

Miyu pours tea into a cup and hands it to me. 

"Here, tea." 

"Oh, thanks." 

As I sip the tea, I glance at the clock and see it's already evening. 

There's still some time before dinner. 

I've been sitting for a while, so maybe I'll go out for a walk. 

"I'm going to the convenience store now. What about you, Miyu?" 

"Ah, I'll come too." 

We get ready and head down to the living room on the first floor. 

Mom is preparing dinner in the kitchen, so I call out to her. 

"Mom, we're going to the convenience store now. Is there anything you want us to get?" 

"Oh, Issei. Perfect timing. We're out of bread and milk, so could you get some?" 

"Bread and milk, got it. Alright, we're off." 

"We're going, Mom." 

"Be careful, both of you." 

---

We leave the house and walk toward the nearby convenience store. 

It's summer, so even in the evening, it's still hot. 

As I absentmindedly listen to the cicadas chirping around us, Miyu hums a tune beside me. 

She's in a really good mood. 

"Hmm hmm~♪" 

"What's up? Did something good happen?" 

"Going out with big bro is fun. Of course, I'm in a good mood." 

"Going out…? It's just the convenience store nearby." 

One thing I've learned over the past month is that Miyu is very clingy. 

Especially toward me. 

For me, having her cling to me like this is really nice. 

It means she's opened up to me. 

She's also quickly opened up to Dad and Mom, and it seems she's become friends with Mr. Suzuki from the house across the street. 

With that, she'll probably make friends quickly at school too. 

She's good at getting along with anyone—that's one of Miyu's strengths. 

As we chat, we arrive at the convenience store. 

But… 

"U-uh…" 

We stop in front of the store without going in. 

The reason? Miyu isn't moving forward. 

I say with a half-lidded expression, 

"You still haven't gotten used to automatic doors after a month…?" 

"But we didn't have these where I came from!" 

"How many times have you said that…? I've heard it over ten times now." 

"Uuu…" 

Miyu lets out a groan and looks at me with teary eyes. 

She's so cute, damn it! 

"Alright, alright! Here, grab my arm like always. That'll work, right?" 

I say that and hold out my arm to Miyu. 

If we have to do this every time we pass through an automatic door, I'm going to be worried about the future… 

"Is that okay?" 

"Well, it's the usual, so…" 

"Thank you!" 

She says that and clings to my arm. 

Of course, Miyu's chest presses against me. 

Squish… 

Whoooooa! 

My little sister's chest is on my arm! 

It's squeezing my arm!! 

It's the usual, but it's dangerous! 

This is dangerous!! 

Bliss is written as "supreme happiness"! 

Plus, the way Miyu looks at me is so cute—it's a double punch! 

Calm down, me…! 

Miyu is my little sister, even if only by adoption. 

And she's someone I was entrusted to protect by Sirius. 

I can't make a move on her! 

Plus, we're in front of the convenience store. I can't get turned on here! 

Calm down, my little brother down there!! 

"W-what's wrong!? Big bro, your nose is bleeding a lot!" 

"Huh!?" 

Again! 

It seems my reason and instincts clashed, causing me to overheat. 

"I-I'm fine. N-no problem… Let's just ask the cashier for some tissues…" 

We enter the convenience store and ask the cashier for tissues. 

"E-excuse me. Can I have some tissues?" 

"It's you again…" 

Since this happens every time I come to the convenience store with Miyu, the cashier seems to have completely memorized my face… 

---

After finishing our shopping at the convenience store, we're now relaxing on a park bench while eating ice cream. 

By the way, I'm eating soft serve, and Miyu is eating a GariGari-kun. 

It's her favorite. She seems to like cola. 

The fridge at home is always stocked with GariGari-kun just for Miyu, so she could've eaten something else… 

Still, my parents are way too indulgent with their daughter! They should cherish their son a bit more too! 

"GariGari-kun is the best!" 

Well, as long as she's happy, it's fine. 

Miyu points to a building visible from the park and asks, 

"Hey, big bro. Is that Kuoh Academy over there?" 

"Yeah, yeah. That's where we'll be taking the entrance exam next year. It's pretty big, right?" 

"Yeah… Do you think I'll pass?" 

"For you, it'll be a piece of cake. If anything, I'm the one who's in trouble." 

No, really. 

Academically, I'm just barely scraping by. 

If it were P.E., I'd be fine, though. 

"Well, let's head back soon. Dinner should be ready by now." 

As we finish our ice cream, it's already a good time to head back. 

"Ah, big bro. I got a winning stick." 

She says that and shows me the winning stick. 

It's definitely a winner. 

Miyu smiles brightly and says, 

"Let's go to the convenience store again♪" 

Looks like I'll have to prepare myself for another nosebleed. 

'Partner, you've really become like a big brother. Except for the part where you get turned on by your little sister.' 

Shut up! 

What else can I do!? 

Miyu has a baby face but an adult body! 

She's got a great figure! 

There's no way I, the embodiment of ero, wouldn't get turned on! 

I'm desperately holding back! 

I, the lump of lust, have been holding back this much—isn't that amazing!? 

'Sigh… If it weren't for that, you'd be the perfect partner.' 

Ddraig, give up. Ero is the source of my power. 

Ero is power, ero is justice! 

That's what my master said, right? 

'Tch, that old man. Teaching you unnecessary things.' 

Well, I was into ero even before I met my master. 

'Can I cry?' 

Calm down, Ddraig! 

If you cry over something like this, what'll happen in the future!? 

You'll die! 

'Waaaaah! Someone help me!' 

Ah, he's crying… 

Sorry, Ddraig. 

"Let's go, big bro!" 

As I'm talking with Ddraig, Miyu tugs on my hand. 

"Alright, alright. GariGari-kun isn't going to run away, so no need to rush." 

I smile wryly. 

Really… Miyu is just too cute! 

'Still, it seems this girl has settled in quite well.' 

Yeah. 

She still seems a bit anxious, but she'll get used to it as time goes on. 

As her big brother, I need to support her properly. 

'Yeah. That girl has a lot on her mind too. It's up to you to support her. I'll help a little too.' 

Thanks, Ddraig. 

You're really the best partner. 

As we have that conversation, we head back to the convenience store. 

Of course, Miyu got scared of the automatic door and clung to me, and I ended up with another nosebleed. 

---

"I'm really tired today." 

After returning home and having dinner, I'm taking a bath. 

First, let's wash my hair… 

"Huh? The shampoo's out." 

No matter how many times I press it, nothing comes out, so it seems it's empty. 

Do we have a replacement? 

The replacement shampoo should be under the sink… 

I open the bathroom door to look for the replacement shampoo. 

And there— 

""Huh?"" 

In front of me is a naked Miyu. 

What a feast for the eyes! 

Wait, this isn't the time for that! 

"Miyu…?" 

"I was about to take a bath…" 

Right! 

That's the only explanation! 

"Ah, then you can go first, Miyu. Just call me when you're done, okay?" 

Since Miyu came here, I've been careful to avoid these kinds of awkward encounters, but… I messed up. 

Having an awkward moment with Miyu is bad for various reasons.

Even as a pervert, I wanted to avoid that. 

…But since the event has already happened, there's no helping it. 

I have to deal with this situation now! 

Then, Miyu responds with something unexpected. 

"I-I'll take a bath with you, big bro! I'll wash your back!" 

"Huh…" 

Whaaaaaat!? 

Are you serious!? 

Is this really happening!? 

"I-I'm happy for the thought, but…" 

"…Is it no good?" 

Don't look at me with those upturned eyes! 

If you say it like that, I'll…! 

"It's not no good! I'll take you up on that offer! Please!" 

I have no choice but to respond like this! 

---

"How is it? Does it itch anywhere?" 

"No, it's fine. It feels good." 

Right now, my little sister is washing my hair. 

"Alright, I'll rinse it off." 

"O-okay." 

"Next, I'll wash your body." 

"A-alright." 

Ah, the pressure is just right—it feels so good. 

Still, why is Miyu doing this? 

We've never taken a bath together before. 

Well, this is the first time we've run into each other naked, but… 

As Miyu continues washing my body, I feel a soft sensation on my back that's different from a towel. 

I remember this feeling! 

"M-Miyu? Don't tell me, you…" 

I cautiously turn around, and sure enough, Miyu's chest is pressed against me! 

"Heave-ho, heave-ho," she makes cute movements as her chest moves up and down! 

"Miyu!? Where did you learn that!?" 

Don't tell me this is how they bathe in the other world!? 

No, at least I didn't know about it! 

As her big brother, I have to correct this wrong knowledge! 

I may be a pervert, but I can be strict about this kind of thing! 

Just as I'm about to scold my little sister— 

"I saw it in one of your naughty videos… I thought you'd be happy if I did this." 

I'm the cause! 

It's hard to scold her when I'm the cause! 

But Miyu, you watched my videos!? 

I thought I hid them properly! 

I am happy! 

My little brother down there is going wild! 

"I can't… I-I'm getting dizzy…" 

For me, who's been holding back so much, this event was a bit too stimulating. 

While enjoying the sensation of Miyu's chest, I burned out completely. 

---

"Where am I…?" 

When I wake up, I'm in my room. 

It's neither heaven nor hell. 

It's definitely my room. 

Then, Miyu's face comes into view. 

"You're awake? Are you okay?" 

Ah, there are tear stains. 

It seems I made her cry by fainting. 

"Yeah, I'm fine. Sorry for worrying you…" 

"I'm sorry, it's my fault…" 

She looks really down, but it's not her fault. 

At that time, I was definitely happy…! 

By the way, I never asked Miyu why she decided to wash my back. 

"Hey, Miyu. Why did you decide to wash my back?" 

At my question, Miyu looks down and says, 

"…Since I came to this world, I've been nothing but a burden to Dad, Mom, and especially you, big bro… I thought I should do something to thank you… But I didn't know what to do." 

I see… So that's what she was thinking. 

I had no idea she was worrying about something like that. 

Since I brought Miyu here, I've only thought about protecting her. 

I wanted her to get used to this world, even just a little, and to be happy and bright. 

I just wished for that and watched over her… or so I thought. 

I hadn't noticed Miyu's worries. 

That's why this happened. 

I pat Miyu's head and say, 

"I understand how you feel, Miyu. Thank you. But we're family, so you don't need to worry so much. As long as you're happy, that's enough for me." 

"…But then, I'm not doing anything for everyone." 

"That's not true. For example, you're teaching me, right? And Dad and Mom have been helped by you in various ways too." 

"Really?" 

"Yeah, really. Want to ask them next time? I'm sure they'll say the same thing." 

Hearing my words, Miyu looks like she's about to cry but wipes her eyes and smiles. 

It seems she's resolved her inner worries. 

"Hey, big bro. Can I ask you one more thing?" 

"What is it?" 

"Can I sleep with you tonight?" 

W-what a cute request! 

Miyu, you're really such a big bro's girl! 

But big bro is happy! 

I'm even moved to tears! 

"Yeah, sure." 

I smile and respond to Miyu's request. 

It's already late, so it's time to sleep. 

I lie down on the bed and open the blanket, and Miyu crawls in. 

She curls up and rests her head on my chest. I mutter, 

"It's been a month since Miyu came here, huh?" 

Well, it doesn't feel like we've been sleeping together, though. 

It's been a month since Miyu became part of the family. 

Looking back, time really flies. 

"Hey, Miyu. That… Miyu?" 

"Zzz… Zzz…" 

Miyu is breathing peacefully in her sleep. 

She fell asleep so fast! 

It hasn't even been a minute since we got into bed!? 

But does that mean she's that comfortable? 

Thinking that, I can't help but smile. 

As I pat Miyu's head, I close my eyes and drift off into the world of dreams. 

---

Miyu has become a proper big bro's girl! 

Also, the prologue will probably end in 1-2 more chapters.