My little sister, Midoriko, was going to be staying at my house for a while. The next morning. "It's hot..."

The first thing I noticed upon waking up was the incredibly muggy heat.

Even after the start of August, the heat only seemed to intensify. "Wait... Midoriko?" "Mm-hmm..." My sister was sleeping next to me.

She was wearing just a pair of underwear and a tank top—a very sloppy way to sleep.

This is a room that wasn't in use.

Since Midoriko was taking over my room, I had moved down here.

But my sister had somehow slunk into my futon without me noticing.

"Get up, Midoriko. You have club practice, don't you?" "...Mm-hmm. ...Yaa."

Midoriko whined like a baby.

Come to think of it, my sister had very low blood pressure. "Hey, I'm telling you to get up." "………………"

With a blank stare, Midoriko looked at me.

"...Wha? ...Big bro?" It seemed she was still half-asleep and confused.

Onitan is how he used to be called.

I don't know when exactly, but I'd become the "oni" (older brother). Back in the day, though, he was pretty clingy with me.

There was an age gap between us, but our sibling relationship was solid.

"...Roshie, is your oni-bro there?"

"Go take a bath and wash up properly." "Hmm~. Hmm~♡"

Midorike clung to my waist, rubbing her cheek against me like a cat. "...You smell good♡" "Hey..." And that's when it happened.

"Okarin~... time for breakfast... already~..."

My high schooler sister, Akari—a blonde beauty—came into my room.

Dressed in an apron, she seemed to have been preparing breakfast. "...Huh?" "Akari, that's not it. This is—"

"Oh, right. I know it's not your fault, Okarin. It must be that girl was sleepwalking and wandered into the futon, right? I understand."

She spoke at a blazing speed while glaring at Midorike with the intensity of a Hannya mask. "Hey, wake up!"

Akari yanked Midorike's arm sharply.

“……hmm? Foreigner? How do you……?”

"What the hell is this idiot talking about……?”

Akari’s forehead bulged with tense veins.

“Midori Lake has low blood pressure. Take her to the bath.”

“Well, I guess it’s fine. Here, come along!”

Akari tugged her little sister by the hand, pulling her firmly forward.

“……Hey. I want more time with my oniitanto… together… Finally, now that he’s gone, we can be together again… mumble mumble……”

Midori Lake staggered as she exited.

The door slammed shut with a batan, leaving me all alone. “……What do I do now?”

In the end, after some discussion, Midori Lake reluctantly agreed to let Akari and the others stay.

But she insisted on keeping watch over them.

Just as I was resolving to face the four of them head-on…

"...No point in overthinking it. Gotta get to work." I got up and started changing my clothes.

I reached for my razor, only to realize Midori was already in the shower. "Guess I'll shave later."

When I walked into the living room, Akari had already laid out breakfast. There were two place settings on the table.

"Here you go, darling ♡ Time to eat ♡" Akari sat down next to me.

Apparently, these were just for me and Akari.

"Oh right, I put my portion in the fridge. Big sister is still sleeping over there."

"Hey, I was about to say I'm sorry about Midori's—" "No way." "I haven't even said anything yet..." Akari stuck her tongue out at me.

"Why do I have to make food for that woman too? I don't owe her that much."

"But you're making portions for me and Nana, aren't you?"

"You're the future husband, but Big sister is just Big sister."

Akari turned away with a huff, like a sullen child.

The two of them really didn't get along. "Come on, don't be like that. I'm asking you for this."

「……Ugh. Fine. Since you're asking, I'll make it just for you, specially」

She puckered her lips into a pout before breaking into a smug little smile that suggested she was hatching some kind of mischievous plan.

「Akari♡ I made it! In exchange, though~……mm~♡」

Akari pursed her lips and closed her eyes. "What?" "A kiss♡ I want one~"

……Should I give in to this?

I didn't have a reason to refuse, not that we had become lovers—even if it was only temporary…… 「Here, mm—♡」 And just then. Whap! Thwack! "Uewp!!"

Suddenly, a damp bath towel slapped onto Akari's face. "Grrr! Gr-!" "Don't move, Akari. I'll take it off." I retrieved the towel.

Akari let out a relieved breath as she glared over her shoulder. "What do you think you're doing?!"

Minori Lake, still fresh from her bath, looked at me and Akari with a displeased expression.

「……Ugh, that's gross. Kissing an old man like this thing on in the morning is so weird」 "It's not like it bothers me! At all!"

By the way, I hadn't told Minori Lake about my relationship with Akari and the others.

Just to avoid the chaos that would ensue if they found out.

「……Bro, you're not gonna fall for the pranks of some damn kids. People are gonna think I'm a pervert.'

'Akari's the pervert, got it! Ow!' I poke Akari in the forehead. 'Morning, Midori Lake.' '...Hn.'

Midori Lake was wearing a polo shirt with a mini-skirt.

A black ribbon tied her long hair up into a ponytail.

She dropped her enamel bag, which read [Alpico Academy], and her ball case onto the ground with a thud.

'...Big bro, drive me to school this morning.'

'Huh!? What the heck! You don't have Akari as your personal driver!'

As Akari lunged at her, my younger sister huffed loudly through her nose.

'...Hah? I know that. I'm just asking.' 'Then just walk there yourself!'

'...Ugh, I hate trains anyway. There are always those creepy old men looking. Staring right at my tits and stuff.' Before I knew it, my sister had grown into quite a young woman.

In the little bit of time since I last saw her, she had become feminine.

There were probably plenty of perverts out there looking at her with lecherous eyes.

I can understand the feeling of hating trains. "Got it. I'll drive you."

"Akari!? Don't get spoiled! You'll start believing anything goes!"

"...Huh? What's wrong with me being clingy to my big bro?"

"Big problem! After all, you two are... uhm, not related by blood, right?"

She hadn't explicitly stated it before, but Akari was the one who brought it up.

"Oh. Yeah. My dad's wife from his remarriage is Midoriko."

My dad's original wife, meaning my mother, passed away pretty soon after giving birth to me.

Some time later, my father remarrried.

Midoriko came into the picture as his stepdaughter from that marriage.

"...Just because we're not related by blood? You think it's gonna turn into one of those shoujo manga or light novel scenarios? Gross." "Don't talk like that!"

I calmed Akari down as she tried to hit me.

"Midoriko. You went too far. Apologize."

"...I don't really hate it. Well, I mean, why are you acting so clingy and affectionate toward a girl who doesn't even like you back, first thing in the morning? Your little sister's got a lolicon complex."

Midoriko puffed her cheeks, speaking with an air of irritation.

"Akarin! Get angry at him! He's been saying rude things this whole time!"

"Ah... but isn't that just how it usually is?"

"Akarin... were you raised being insulted? Is there some chance... you're a masochist?"

"Absolutely not. Midoriko, stop making a fuss in the morning. Akari, I'm sorry. My little sister is being rude."

Akari frowned with a look of displeasure, but soon let out a sigh.

He retreated to the living room once and came back with breakfast he had made. "Here, this is for you."

He brought toast, salad, coffee, and ham eggs. "...?" "What?"

"...Tch! Playing nice just to make me feel indebted to you."

"Hah? Then please don't eat it, no problem there?"

"...Big bro. No matter how good a cook you are, it's better not to date such a nagging old hag." "Who is an old hag, hm~♡"

Niko, Akari smiled with a perfectly radiant grin.

I could tell she was on the verge of exploding.

"H-Hey... hurry up and eat your breakfast. I'll walk you to work."

"...Aah, yeah, I want rice for breakfast though."

"Y-You f-fucking (※Self-censored)"

Leaving Akari seething in the background, Midori-ike hurriedly finished her morning meal.

"...Finished eating. It wasn't bad at all." "Thanks for having us!"

Akari cleared the dishes away with rough movements. "...So, Onii-san."

"Mm. Akari, I'm just heading to work as is." "Mm. Okey-dokey."

Together with Midori-ike, I headed toward the genkan. "Okarin! Forgot something~"

Pat-pat, she ran over and handed me a package.

"It's a bento ♡ I packed it with tons of love!" "Is that so. Thanks." I petted Akari on the head.

Akari laughed happily, making a "funa-funa" sound. Geshi!

"I-it's so... Mido-lake, what is it with you?" "...Stop being all lovey-dovey, you're dead!"

Mido-lake huffed, flared her nostrils in a snort, and went ahead of me out through the genkan.

"Thanks, Akari. I'm heading out." "Mm ♡ Take care~"

With a smile on her face, Akari gave me a kiss on the cheek. Smooch ♡

Pulling her face away, Akari flashed a bright smile and waved.

"That was a good-morning kiss ♡ I'll do it every day from now on ♡" "Ah, ah... take care." Once I stepped outside the genkan...

My little sister was standing there, glaring at me with a sour look.

"...You're late. What were you doing?" "Uh, well..."

I couldn't exactly tell her that I'd been exchanging good-bye kisses since morning.

"Hey, I'll go around to pull the car out. Just wait a sec." I headed to the garage and backed the car out.

Opening the trunk, I loaded the luggage inside, and my sister took the passenger seat.

"I mean, I'm literally sitting in the backseat, right?"

"......You're so damn noisy. Just drop me off already."

Well, it was up to my sister where she sat, technically.

I pulled the car out and headed toward Alpico Academy.

"...Bro. Every morning, you're... eating that thing she made by hand?"

Midoriko fiddled with her phone, tapping at it idly, asking with a completely blank expression. "Mm-hmm." "...So every day, something as tasty as that?" "Yeah. It's been a real lifesaver."

"...What the hell? You don't have a housekeeper. What are you making her cook for you?"

"Tsk," Midoriko clicked her tongue.

"I told her I'd make it myself, but she won't listen. She says cooking is a hobby of hers."

"...Hah? That's an absolute lie. She's definitely trying to win your favor by hooking you with the food and getting herself under your roof."

That was true, except in Akari's case. I couldn't just flatly deny it.

"...Argh, that woman is such a pain! She really is so in the way! It was supposed to be just me and my brother..." "You and you?" "...Nothing."

Pfft. Midoriko turned her head away with a sharp huff.

Her attitude toward me changed drastically once she hit middle school.

So this must be what puberty is all about.

Come to think of it, I was irritated over everything back then too.

"……Hey. How long do you plan on sticking around with those guys?"

She asked while we waited at the traffic light.

As always, she didn't take her eyes off her smartphone. "Nah, I haven't really thought about it."

"……Huh? So you're just gonna keep supporting them for life? That's rich. You really are a sucker for being used." "That's not it at all." I answered clearly. I would never be a slave to anyone.

"Akari and Nako are both my precious……" "……Precious?" If this had been before, I would have called them my students. But things are different now, undoubtedly.

But I couldn't just put on that front.

"……Seriously, you're so annoying. Both them and you."

She pulled a Chupa Chups from her skirt pocket and stuffed it into her mouth roughly.

"Don't just eat sweets all the time, you're supposed to be the ace and captain of the basketball club, aren't you?"

My sister is a student at a prestigious school with a top-tier basketball program, where she serves as captain.

She's incredibly talented. Talented enough to have earned a sports scholarship admission.

"...Shut up. Whose fault do you think it is that people think I'm taking them for granted?"

Midoriko snapped a piece of candy between her teeth with an audible crunch.

She might be feeling stressed out due to living with someone she isn't used to.

Before long, we arrived in front of the school. "I'll pick you up on the way back."

"It'll be 7 PM, but that's fine if it suits you." "...Mm. I'm counting on you."

Holding her luggage, Midoriko stepped out of the car. "Well, good luck with club practice." "......" "Midoriko?"

My sister stopped in her tracks, looking around nervously. "...Nii-san." She turned back to the driver's seat.

She shoved the Chupa Chups she had been holding in her mouth into mine. "...Bye-bye♡"

"A-alright... If you don't need it, just throw it away."

“...You're so noisy. Stupid, stupid big brother ♡”

With that, Midoriko ran away at a quick pace.

...Pubescent girls really are impossible to figure out what's going on in their heads....