DISCLAIMER
First, all characters in this book are of legal and consenting age...
Second, despite terms like brother and sister, the characters are not blood-related-they only grew up together due to adoption.
Finally, any reference to their childhood/past isn't intended to sexualize them as minors but to give them more depth
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Oda Satoshi was just your average high schooler, the kind of guy who sat glued to his computer screen after cram school. But today wasn't just any day. Today, Winter-sensei—the food and music blogger he admired—was dropping a brand-new song at exactly seven o'clock.
For Oda, this wasn't just entertainment. No, this was destiny.
He clicked into Winter-sensei's channel early, waiting in the "works" section like a loyal disciple. "Music is always better when there's a video," he muttered to himself, bouncing slightly in his seat. "That way it feels like a full-course meal instead of just a snack."
This time, though, he was especially nervous. Because this song? This wasn't just any release. Oda was secretly planning to borrow it. To confess.
Yes, confess!
He wanted to pour his heart out to his personal goddess, the girl who had made his boring school days feel brighter. If Winter-sensei's track was even half as good as the previews promised, then Oda was ready to ride that melody straight into romance. He could already picture it: he'd send her the link, and when she asked why, he'd reply, Because these lyrics are how I feel about you.
Smooth, right?
…Except there was one tiny problem.
Winter-sensei himself had clearly said during last week's livestream, "This song isn't really suitable for confessions, guys. Don't get any weird ideas."
"Tch. What do you know, Winter-sensei?" Oda clicked his tongue, puffing out his cheeks in defiance. "You're just the singer! Whether it works or not is up to me. Baka."
Even as he said it, his heart thumped faster. He refreshed the page—and froze.
"…Kasumi Utako?"
The title of the new work jumped out at him, three characters framed against a stark black background. As a longtime fan, Oda instantly recognized the name. Kasumi Utako was a light novel author Winter-sensei had been hyping nonstop lately. Every livestream, every side comment, he found a way to bring her up. At first, Oda thought it was sponsored promo, maybe some sneaky ad deal. But now? Seeing her name headlining this release?
"Ohhh… I get it." Oda smirked knowingly. "Winter-sensei's totally smitten with her, huh? That's why he keeps spamming her name."
Still, gossip could wait. With trembling fingers, he clicked play.
A soft, melodic intro poured through his headphones, light and refreshing. The sound wrapped around him like a gentle breeze on a sunny afternoon, cherry blossoms drifting across a blue sky. Without meaning to, Oda's head bobbed to the beat, his legs tapping beneath the desk. "Not bad, not bad… This is fire."
Then the video kicked in. Onscreen, a slightly taller loli and a slightly shorter shota stood back-to-back in a wide sea of blooming rapeseed flowers. The art was almost dreamlike, but Oda barely glanced at it. His focus locked on the melody, waiting for the voice to drop.
And when it did—
A delicate, emotional boy's voice slipped into the rhythm:
[My Sister I really, really love you I hope you can choose me…]
"Eh—!? Huh!?" Oda's jaw nearly hit the keyboard. "Did he just… say sister?!"
He paused the video for a split second, blinking hard. Maybe he misheard? But no—the subtitles were right there. Crystal clear.
"…An older sister from next door, maybe?" he muttered. "If it's like that, then yeah, this really isn't suitable for my confession…"
Regret pricked at his chest, but curiosity won out. He hit play again. Onscreen, the imagery shifted: a little girl in a yukata, cat mask tilted playfully atop her head, buying cotton candy at a summer festival stall. The atmosphere was nostalgic, almost painfully sweet.
"Wait… no way. Could these be… Winter-sensei's childhood memories? Him and his older sister?" Oda leaned closer to the monitor, half-astonished. If that was true, then the guy was way more romantic than he'd imagined. Still… how could a mere mortal like Oda compete with childhood snapshots and festival scenes? He barely even knew his goddess outside of class!
He sighed, shoulders slumping. But he kept listening. At the very least, maybe he could steal some courage from the lyrics.
The song swelled:
[Let me protect your bright and brilliant smile, And your playful, charming eyes— They're already overflowing, Having long surpassed the boundaries of siblings…]
A warmth spread through Oda's chest. His heart melted at the sweetness, even if it wasn't meant for him. Onscreen, the shota had grown taller, finally catching up with the loli. The two walked hand in hand through a forest painted red with autumn leaves.
Then the tone shifted. The music deepened, carrying a faintly dangerous edge:
[Forbidden love takes root and sprouts, Blue roses quietly bloom…]
"H-HUH!?" Oda yelped so loudly his mom probably heard from the kitchen. "W-Wait, wait, wait—actual sister!?"
A cold shiver shot down his spine. He slammed the pause button again, leaning back in his chair with wide eyes. His scalp prickled, goosebumps rising. "Winter-sensei… are you serious right now? You're actually going there?!"
He clutched his head, groaning. "Damn it, he's too fearless! Straight-up aiming at forbidden territory! This isn't just gutsy—it's insane!"
Without thinking, Oda scrambled to the comment section. The video wasn't even out for long, but the chat had already exploded in chaos, comments flying faster than he could scroll.
"Really, fake!? Winter-sensei, are you confessing to your actual sister!? Σ(｀д*ノ)ノ!"
"The people in the photo… are those Winter-sensei and Kasumi Utako-sensei!?"
"You two are siblings!?"
"Forbidden love! This is too exciting!"
"I'm losing it! My heart can't take this, kyaaa!"
"This is unreal, totally unbelievable…"
"I don't even know what to say anymore, I'm shocked beyond words!"
"To be fair, this song 'Kasumi Utako' is insanely good. The melody is catchy, the vocals are so delicate and emotional—it really makes you want to fall in love… but this subject matter, man, this is dangerous!"
"Winter-sensei's psychology might be a little… twisted, don't you think?"
"Actual sister is wrong! Winter-sensei, dump her and come to me! I can be your sworn sister!"
"Ridiculous! Too ridiculous!"
"I'm such a baka… oh no, my brain just short-circuited!"
"The blue rose represents an impossible dream, right? It symbolizes forbidden love… this guy really leaned into it."
Oda Satoshi was cracking up, hands over his mouth as he read. He couldn't resist tossing in a few comments of his own, laughing and gasping along with the chaos. But then—one particular comment caught his eye, highlighted at the very top with thousands of upvotes.
"Oh my god, I'm truly impressed by this sibling pair! The sister poured her feelings for her younger brother into a light novel, and it turned out amazing. The younger brother composed his feelings into a love song, and it's honestly beautiful. I'm stunned by their creativity!"
"…Wait, wait, wait. What!?"
Oda Satoshi blinked in disbelief.
"The sister wrote… a light novel? About her brother!?"
He usually didn't bother with novels—music and food videos were more his scene. So he hadn't even glanced at Love Metronome, the book Winter-sensei (Kasumigaoka Touji) had been shamelessly plugging in every livestream.
Now though, his curiosity spiked. Clicking Expand Replies, he dove deeper into the gossip.
"The younger brother in Love Metronome is totally based on Winter-sensei, right?"
"Both siblings are insane! Super talented, too!"
"High schoolers these days are competing on another level. Songs, novels… as a senpai, I feel completely outclassed…"
"Hold up, so Kasumi Utako-sensei's novel is basically the story of her and Winter-sensei!?"
"Wait, I remember—wasn't the younger brother in Love Metronome adopted? Could Winter-sensei also be adopted!?"
"Hah!? Don't joke like that, baka. It's probably just her imagination spun into a story."
"No, no, it feels too real to be coincidence!"
"If that's true, then… aren't they basically in a mutual crush? Oi oi oi, their parents must be losing sleep over this."
"Love… Metronome…" Oda Satoshi muttered, repeating the name under his breath.
He rubbed his chin, his eyes sparkling with the kind of curiosity only gossip could ignite. Normally he would never waste money on a light novel, but now—now he needed answers! His house was only a few minutes from the nearest bookstore, anyway…
Glancing out the window, he hesitated for all of two seconds. Then he jumped up, grabbed his phone and wallet, and dashed out of his room like a man possessed.
As for his original goal of finding courage to confess to his own crush? Yeah, that was long forgotten. Winter-sensei's chaos had completely derailed him…