That night— It was already past eleven when they got home, and by the time everyone had finished showering and winding down for bed, it was well after midnight.
When Kasumigaoka Touji woke up the next morning, the clock was a little past seven. He rubbed his eyes and sat up with a groggy yawn, the lingering effects of too little sleep weighing down his limbs. Still, he pushed off the blanket and stood up.
"Nngh..."
As he opened his door and stepped out into the hallway, he was greeted almost immediately by a familiar voice.
"Morning, Otouto-kun."
"Morning, Utaha-chan."
Right on cue, Kasumigaoka Utaha appeared, stretching slightly as she walked toward him.
Touji blinked at her outfit.
She wore a dark gray oversized hoodie with the hood hanging down her back. Beneath that, her long legs were clad in thin black stockings, the fabric hugging every curve and glinting slightly under the morning light.
This was the very outfit he'd picked out for her the day before.
Well, almost. Technically, the hoodie was long enough to cover the black super short skirt he'd chosen to go with it, but now he couldn't even tell if she was wearing it.
She had to be, right?
Touji glanced at her lower half again, subtly trying to confirm.
"Hmm? What are you looking at so intently, Touji-kun?" Utaha tilted her head and gave him a sly smile.
"Are you wondering if your dear older sister is wearing anything under this? Want to lift it and check for yourself?"
Touji raised an eyebrow, grinning mischievously. "Can I? I mean, if you're offering..."
And with no hesitation, he lightly pinched the edge of the hoodie and lifted it.
Beneath it, the hem of a skirt was indeed visible.
"As I thought."
"Come, follow me to the police station! The charge is indecent assault!"
Utaha instantly grabbed his hand, gripping it like a vice.
"Oi oi! You just said I could check!" Touji protested, trying to pry his hand free.
"Hmph~ I don't recall giving permission. But if I did, you should have known it was a trap!"
Touji groaned and quickly pulled away, jogging down the stairs in mock retreat. "I'll remember this betrayal!"
"A sister's job is to test her foolish Otouto-kun!" Utaha called after him, her lips curving into an impish smile as she followed.
After their playful banter, the two alternated using the bathroom and brushing their teeth before making their way to the dining table.
Their parents, already seated, gave them the usual round of parental instructions before departing.
"Make sure to clean up after yourselves. Don't forget to lock the doors when you leave, and double-check the stove!"
"Yes, yes..." Touji replied, nodding sleepily.
Once breakfast was over, they all walked out together.
Kasumigaoka Eiji flagged down a taxi while Kasumigaoka Airi double-checked their luggage.
Touji and Utaha stood by, waving as their parents drove off.
As the car disappeared around the corner, Touji turned to his sister.
"Well, now it's just us."
Utaha tucked a loose strand of hair behind her ear and said, with a deliberately sultry tone, "Alone with your beautiful older sister. Are you excited, Touji-kun?"
Her wine-colored eyes shimmered with playful allure.
Touji met her gaze calmly. "Did you forget we've already lived together for over a decade?"
"But this time... it's different."
"Hmm... True. This time, there's no one else here."
He closed the front door and, after a slight pause, locked it with a soft click.
Kasumigaoka Utaha heard the distinct click of the lock, and her heart gave a small jolt. Even her steps, normally graceful and measured, grew slightly awkward.
W-What's with locking the door in broad daylight…?
She could feel it.
The intensity of that burning gaze boring into her back—so blatant, so shameless—it made her spine tingle.
And yet, buried beneath that nervous flutter was something else entirely… anticipation.
Her heartbeat sped up. Even her breaths unconsciously grew softer, quieter.
Just then—
"Ding-dong—"
The sudden chime of the doorbell shattered the moment like a dropped teacup, snapping the two of them back to reality.
Who on earth…!?
Kasumigaoka Touji furrowed his brows, visibly annoyed as he muttered under his breath.
"Tch, timing couldn't be worse."
He turned around and made his way to the entrance.
Utaha also turned, arms crossed under her chest, lips pursed as she stared toward the door like a queen disturbed during her tea ceremony.
The door slid open.
"Good morning!" came a bright, slightly exasperated voice. "Oh? You're both here? Wait, did you two just have a fight or something?"
The visitor blinked at the tense atmosphere.
It was none other than Machida Sonoko-san, Utaha's long-time editor.
She was dressed like the epitome of a working adult: black office lady blazer, pencil skirt, translucent black tights clinging perfectly to long, shapely legs, and faint makeup that accentuated her features without overpowering them. Her rose-pink lips curled into a half-wary, half-curious smile.
"Ara, Editor Machida~" Utaha spoke first, her voice laced with cool amusement. "You really know how to ruin the mood. My dear Otouto-kun was just about to confess to me, and you had to barge in."
"E-EHHH!?"
Machida froze, her eyes darting between the two like a robot short-circuiting.
"W-Wait… You mean that kind of confession?"
"The exact kind you're imagining."
Touji sighed as Utaha delivered the line with a straight face, not even a twitch of her lips.
This girl seriously had no mercy.
He glanced sideways at her. Ever since that strange night where their parents hinted—no, practically spelled out—that they weren't blood-related, Utaha had been a bit too eager to push boundaries.
Not that he minded… much. But still!
"Hold on! HOLD ON A SECOND!!"
Machida-san flailed her arms in disbelief.
"Are you telling me… you two are—biological siblings?! Isn't this like, totally against the law!? Like, completely forbidden!?"
Her voice rose an octave.
Touji grimaced.
"Isn't this an ethics and morality violation of the highest degree? Are you guys even taking this seriously?!"
Machida-san was practically on the verge of tearing her hair out.
Utaha, on the other hand, calmly placed a hand on her hip and said with serene indifference, "As long as there's love, what does it matter if he's my Otouto-kun?"
"There's a huge problem, okay!?" Machida-san nearly exploded. "And stop quoting your own novel! It works in fiction, sure, but in real life this is a whole different story!"
Her forehead was starting to visibly sweat.
Touji finally stepped in to stop the madness.
"Relax, Editor Machida. Utaha-chan and I aren't biologically related."
"…Huh?"
Machida froze.
"It's true," he said calmly, handing her a pair of indoor slippers. "So please, come in before your blood pressure spikes."
"…O-Okay…"
Still a bit shaken, she bent down, swapped her heels for the offered slippers, and stepped into the house.
…