Early August.

Coming home from summer break, I found my little sister, Midoriko, waiting at our house.

This is what happened that night when we got back from the trip. "Midoriko. Come in."

My sister had holed up in my room.

I knocked on the bedroom door and heard a click... the lock undone inside.

"Midoriko... this is my room, you know."

A high school girl was sprawled out on the bed.

Long, slightly tousled hair with a reddish tint.

Tied up into a ponytail with a black ribbon.

A somewhat stern expression and a slender figure.

Her thighs were particularly tight and toned. She was Okaya Midoriko. My sister, more or less.

Midoriko was lying face-down on the bed, scrolling through her smartphone.

"…Ah, yeah. I'm using this room, so mind your manners."

"No, this is my room, and that's my bed."

"…Shut up. It's already decided; I'm staying here."

My little sister wrapped the towel sheet around herself, curling up into a tight ball like a roll of sushi.

"Not that, why are you even here?"

"…It's all about club activities this summer. It's just closer to the main house from school than where we actually live."

An enamel bag sat by the side of the bed.

[Alpico Academy] was written on the surface of the bag.

Midori Lake is in a club.

"Wasn't Alpico supposed to be further from here…?"

"…Shut up. I got permission from Mom and from [Shuu] too." "And your dad, too…?"

He didn't say a damn thing back……

"……Well, this summer I'll be commuting to club activities from Onii's house."

"Well…… that's not a problem in itself."

Nyu. She pokes her face out from the towel blanket she was rolled up in.

……Even though she's my little sister, she has a pretty face.

She pulls up the corner of her mouth in a smirk. "Nii…"

She twiddles the stick of the Chupa Chups she’s been holding in her mouth, pic-pic, pic-pic.

"You shouldn't eat so much candy all the time, it's bad for your health." "……That has nothing to do with Onii."

Midoriko clutches my pillow tightly against her chest and takes a deep breath. "……Suuu, haaah. That calms me down."

Like a cat basking in the sun, her sister’s expression melts into a soft shape. "……Onii. Nn."

Pon-pon. She pats the empty space next to her with her hand.

As I sit on the edge of the bed, Midoriko rests her head on my knee.

So that was her signal for a lap pillow.

"…So, big bro. Who were those girls from earlier?"

Midoriko looked at me, her gaze heavy with disapproval.

"I told you, I was working as a tutor for cram school while in college. They were my students back then."

"...I see. So why are your former students living with you?" "Well… it just kind of happened like that." I briefly explained the situation.

How, on the night Misae cheated on me, the Ina sisters showed up at my house.

They were dealing with some issues at home, and I was the only one they could turn to.

I told them I was taking them in for protection.

"...No, that's basically kidnapping." Midoriko frowned.

"Come on, I didn't just abduct them or anything…"

"...Big bro. No matter how much you need a hit of sex, having high school girls living in your house is a bit too much, don't you think?"

"I said it's not like that. They were just in trouble and nowhere to go, so…"

"...Even so, isn't it weird to have minors in your home without the consent of their parents?"

“Fuuuh,” Midoriko blew through her nose, staring at me with a look that could have melted stone.

"…… It's just because she has big tits, right? That's why you set it out." "Hardly. I deny that categorically."

"…… Why? A-ashi's got decent knockers too. Why don't I get one?" "Don't be an idiot."

I stuck my finger against Midoriko's forehead with a soft tun.

For a split second, her face softened into a pouty expression before snapping back to its usual stern scowl.

"…… Aren't the other girl's parents angry about it?"

"Seriously. There's been no sign of any contact from their side. I got their home number and called it over and over, but it's dead silence."

"…… Just go straight to the guardians' place then."

"I did. It was an empty shell."

Apparently, Akari's parents didn't want to keep their daughters around.

According to the neighbors, once Akari and the others left home, the parents packed up and fled without a second thought.

"…… Why did the parents abandon them?" "No idea."

"…That's the important part. Why won't you say?"

"It's not right to force people to talk about things they don't want to discuss."

"…No, leaving someone at your house without telling them exactly what's going on—that's messed up if you ask me."

Furrowing her brow and making a scowl, Midoriko said. "…Ahshi hates them."

It seems my sister had a real thing against the Jk sisters.

"They're struggling too, you know. They've got their own problems."

"…So what? They didn't have to go to Ahshi's brother's place just because of that."

Midoriko sat up and shoved me back with a whump.

She mounted my chest, grabbing the front of my shirt. "…Haa. So you did it?"

She was probably asking in a sexual sense. "Don't be stupid."

"…Huh. Really? Why not? You had those two pretty girls right there… why didn't you hit on them? Is your brother's thing impotent?" I pushed Midoriko away. She fell back onto her back, panting heavily.

"I just didn't feel like screwing the guys who came to me for help when they were in trouble."

“...didn't【we】? Why the past tense?”

Midoriko gave me a sidelong glare. ...She's a tough one, this girl.

"...Well, whatever. It's just that I don't want your older sister getting any closer to me."

From her fallen position, Midoriko executed a backbend, spun around in the air, and landed standing up.

"You... saw under my skirt..."

"...Huh? I'm wearing spats. What you saw is nothing to be worried about."

"Sorry, but you weren't wearing any spats..."

Midoriko's face flushed red, and she hastily pressed down her skirt. "...I didn't see! Not that I saw anything!"

"I didn't say anything! It's not my fault you did that acrobatic move; I couldn't help seeing."

"...Ugh, damn it! Shut up! Idiot! Creepy big brother! Perverted old man!"

Midoriko kicked at my legs. Thump, thump.

"But I'm not a perverted old man..."

"Keeping a woman who's ten years younger than you as your harem and claiming you're not a loli-lover is actually fucking hilarious."

Midoriko let out a dismissive snort through her nose and closed the distance between us.

"...Nii-san, kick those bastards out." "That's impossible... mmmph"

She shoved the Chupa Chups she'd been holding into my mouth with a precise pop.

"...They're such a pain. They're just getting in the way of our exclusive, two-person life, Ashi and I."

With a wet pluck, she pulled the lollipop out again.

"You could just move in with them if it's that important to you."

"...Hah? That's impossible. Those women are seriously annoying. They make me sick."

Midoriko put the Chupa Chups she was holding back into her own mouth.

"You really have no shame... that's dirty, you know."

"...S-shut up. It's not like it's dirty or anything. It tastes good... hmm..."

She still has such a childish side to her.

For as long as I can remember, she'd always hand me her uneaten leftovers and then, for some reason, snatch them right back.

"Anyway... just get along, alright?" "..."

Midoriko's gaze fixed on the door, a piercing stare.

She stepped close and slammed a thug-like kick against the wood. Thud! "'Ughh...!'"

From the other side of the door, there was a heavy thump as someone collapsed. "...Tch!"

Midoriko yanked the door open violently.

There, Nako and Akari lay crumpled on the floor.

"...Eavesdropping. You guys sure are full of nerve."

With a punk-like attitude, she crouched down in that spot, glaring at Nako and the others.

"Hii...! Akaarii~..."

Hugging her little sister's body was Nako, the black-haired high school girl elder sister.

On the other hand, Akari, the younger high school girl sister, had her blonde hair tied up in side tails.

"Isn't it a bit much to just kick the door open right off the bat?"

"...Hah? Excuse me? You're eavesdropping on an important conversation between my older brother and me. That's seriously unacceptable, don't you think?"

Midoriko Lake and Akari glared at each other.

"But he locked himself in his room and hasn't come out all this time. Worrying about him is only natural, isn't it?"

"...Hah? And what exactly are you to my brother?"

"His prospective fiancée, but what of that?"

Crack! Something shattered loudly. "H-My teeth...?"

"No, sis, that was probably just the candy stick he was chewing on."

With a pfft sound, Midoriko Lake blew out the candy stick she had been holding in her mouth.

It struck Nanako's forehead with a dull thud. "Oww..."

"Isn't that just rude of you?"

"...Not quite as rude as you, I suppose."

At a distance where their faces were practically touching, Akari and Midoriko glared at each other.

"……Seriously, you're in the way. Get out of my brother's house."

"This is my house, though? When exactly did it become yours?"

"……My brother and I are siblings. And since I'm family, my brother's home is just as much mine as it is his."

"You're the one who waltzed in here without telling Akari-chan. I'd think twice about that. I mean, lacking in consideration aside for being family... you're just getting in the way. Sibling complex."

"W-What?! Who—Who has a sibling complex!"

Blushing crimson all the way up to her neck, Midoriko screamed.

"Anyone can see it. You really love your big brother, don't you~?"

Akari let out a soft, mocking chuckle.

"You're about the same age as us, right? And even now that you're that old, you still adore your big brother."

"……Shut up! It's not—it's none of your business!"

Thwack. Midoriko slapped Akari's cheek.

「Aiee! What the hell do you think you're doing?!”

Akari knocked her little sister back with a sharp slap. “……Get outta here!”

“Says the one who needs to get lost!”

As they started grappling in a brawl, I frantically pinned Midoriko from behind. “Stop it, you idiot!” “………………”

The moment I held Midoriko tight from behind, my little sister went silent for a split second. “Konnnya roo! (Get lost!)” “……Akari, don't do that, okay?”

“Let me go, big sis! I can't kill him if you're holding me!” “……It's bad to want to kill someone.”

Akari was screaming and thrashing about in a panic.

On the other hand, Midoriko was as quiet as a cat who didn't belong there, completely subdued.

“Midoriko. Can we talk now that things are calmer?” “…………Mm-hmm.”

When I tried to let her go, she grabbed my arm tightly.

“……Just keep this going for a little longer.” “Huh? Ah... sure...”

Watching our scene, Akari raised her brows in anger and said.

"Karim! I... hate him!"

On the other hand, Midori Lake also looked at me and said.

"...Bro. Like, I seriously hate this guy."

I sighed and told the two of them.

"At least, let's get along, both of you."

Akari and Midori Lake chimed in unison. "No fucking way."