Night had fallen.
When Yuki reappeared in his room, he glanced at the clock on the wall.
Just as he expected, only about an hour had passed—despite him traveling thirty years into the past.
"Phew… finally back."
He let out a long sigh of relief.
Now that this major task was over, it felt like a heavy weight had been lifted from his shoulders.
Since it was still early, Yuki decided to take a quick shower before talking things over with Mio.
But right when he took off his clothes and was about to step into the bathroom—
BAM!
The door suddenly burst open.
"Big bro! Come play with me—"
Kotori, with her signature red twin-tails and black ribbons, barged in like always, without knocking.
And the first thing she saw?
Yuki, completely naked. Every part of him in full view.
"…Kotori. How many times have I told you to knock?" Yuki said with a sigh as he quickly reached for a towel.
But it was too late. The damage was done.
The white Kotori—the cheerful, innocent version—would always knock.
But the black Kotori, the sharp-tongued commander version? She acted like his room was her own.
Her face turned bright red. Her heart raced so fast she could barely speak.
"Y-You idiot! What the hell are you doing?!"
She slapped her hands over her eyes—though her fingers left a small gap for peeking.
Her thoughts were going haywire.
'Big... It's... that big?'
She swallowed.
"Exactly what it looks like. I'm going to take a shower," Yuki said calmly.
"It's been an hour! How are you not done already?!"
"Y-You perv! What's wrong with you?!"
But even as she yelled, her mind was spinning.
'H-He won't notice if I just peek a little, right…?'
That one glimpse of his body kept replaying in her head.
Her heart thumped faster. Her skin tingled. Even her ears were burning.
Yuki noticed how flustered she was but didn't say anything. Instead, he smirked and turned away.
"I had something important to do earlier. Anyway, I'll take my shower now."
"When I'm done, I'll come play games with you."
He said it casually as he stepped into the bathroom, leaving Kotori frozen in place.
She stood there, stunned, until the sound of water running filled the room.
Finally, she lowered her hands.
Making sure he wouldn't come out anytime soon, she flopped face-first onto his bed, burying her head in his pillow, the lingering warmth and subtle scent making her cheeks glow even brighter.
She kicked her feet softly, trying to calm herself, but her pulse refused to settle.
"Mmhh... Stupid big bro~~~"
A muffled whine escaped her lips as she squirmed, still blushing hard.
Then, her eyes landed on the pile of clothes Yuki had just taken off.
Her face turned even redder.
She glanced around nervously… and slowly reached toward them.
"Wait—no! Kotori, don't! This is wrong!"
Her hand froze mid-air.
But after a second, it crept forward again.
"I-I'm just checking my big brother's health! I'm being a responsible sister!"
"It's not like I'm doing anything weird!"
She grabbed them.
Clutched the fabric tight against her chest. Her nose pressed into his shirt first, then the waistband of his boxers.
Her small body trembled. Her thighs squeezed together instinctively.
"hah I-I'm just making sure he's not overworking himself! haaah~ T-Totally normal behavior!"
For the next ten minutes, she lay curled up on his bed, clutching his clothing, her face buried in it, whispering complaints to herself—her skin tingling, her mind filled with racing thoughts she didn't want to admit.
....
Eventually, she sat up, her gaze drifting toward Yuki's laptop.
In this world, most high-end tech—especially computers—was made by Infinity Enterprises, a global mega-corporation that even handled military contracts. Everyone knew their name.
"…Huh? It's not locked?"
The laptop screen was still on. No password.
Curiosity took over.
She grabbed the laptop and started clicking around.
"Huh? A browser?"
She noticed a minimized tab and clicked on it—
—and was immediately hit with a wall of pixelated blurs.
"Wha—?!"
The blush she had just started to control came flooding back, full force.
"W-WHAT THE—?! So THIS is what he was doing for a whole hour?! He was watching… this?!"
Her imagination took off on its own.
He wasn't just watching it. He was definitely doing something else too.
Her heart pounded like crazy.
"S-Such an idiot! Getting all worked up over this…"
"When he's got a super cute little sister right here… he could've just… asked me…"
"I-I could've helped him, you know…"
Her voice dropped to a whisper as she blushed even harder.
She kept scrolling—curiosity now fully lit.
"I-It's not like I'm into this or anything! I'm just correcting my brother's bad habits!"
"And to do that, I need to do proper research! That's all!"
"Totally reasonable!!"
She clicked through the files with a serious expression.
But the more she looked, the more confused she became.
White hair. Big boobs. Mature onee-sans…
She glanced at the artist's name on the screen: Raihaken.
Then her eyes flicked to the account username.
Her mind froze.
Wait a second.
She thought he was just someone who watched this kind of thing.
But no.
He was the one who made it.
Right now, she wanted to go online and scream:
"So, My Big Brother Is Secretly a Doujin Artist… What Do I Do?!"
But this was her brother's work.
So, as a caring sister, she couldn't just walk away.
No—she had to study them thoroughly.
With a serious face (that totally didn't have other motive), she opened the full collection.
He had only published five works.
But those five?
Masterpieces.
The art was insanely detailed—more polished than most professionals.
Every single one had topped the charts in its genre, selling out again and again.
Even people who weren't into doujinshi had heard of them.
He held the top five spots in the entire industry.
Kotori finished all five in just ten minutes.
Her face was still red—but now, she looked angry.
"That damn brother of mine… Not a single imouto-themed one?!"
"They're all mature women! What's so great about those big-breasted onee-sans anyway?!"
"He lives with a cute little sister and he never once draws her kind?! Just MILFs and onee-sans?!"
"And the way he draws them… it's way too realistic!!"
She kicked the bed, gritting her teeth.
How could he do this?!
She was right here—his actual little sister—and he never even glanced in her direction creatively.
Instead, he was obsessed with older women.
Unforgivable.
"Ughhhh!!"
She punched the mattress over and over, her jealousy and frustration boiling over.