Chapter 4: Adult Brains, Teen Bodies

If anyone ever wrote a manual about how to survive being emotionally thirty but physically seventeen, Yuki would have bought five copies, highlighted them, created notes, and still complained it wasn’t enough.
Because by second period, she was already done with life.
Her head rested on her desk while the teacher explained something about quadratic equations. Normally, Yuki would’ve been alert, taking notes neatly. Today she looked like a retired office worker forced to repeat high school against her will—which, to be fair, was exactly what she was.
Mina poked her arm. “Are you sick?”
Yuki lifted her head slowly. “I’m tired.”
“You slept early last night.”
“I’m tired on multiple levels.”
Mina frowned. “Physical or emotional?”
“Yes,” Yuki said.
Mina stared. “That’s not how— never mind.”
Behind her, Ren sat up straighter than any normal teenager had ever done in the history of teenagers. His posture was perfect. His expression serious. And worst of all, he was actually paying attention.
The teacher looked at him suspiciously.
“…Aoki-kun.”
Ren snapped upright. “Yes, sir?”
“Are you… okay?”
Ren nodded. “Of course.”
“You’re listening. You’re… taking notes.” The teacher pressed a hand to his chin as if witnessing a miracle. “You even highlighted something.”
Ren blinked. He didn’t remember highlighting anything. Apparently, adult instincts had hijacked his body.
The teacher narrowed his eyes. “Are you the same Aoki from last semester?”
Ren considered lying. Then decided the truth was easier. “I’m trying to improve,” he said plainly.
Mina turned toward Yuki, whispering, “He said that with sincerity. I’m scared.”
Yuki rubbed her forehead. “Me too.”
When the teacher called out names, the roll call went smoothly until—
“Aoki Ren.”
“Present,” Ren said.
Not just present. Fully adult-present. Polite. Clear. Responsible. Like a man who paid taxes and worried about electricity bills.
Half the class turned to stare.
“Did he eat something weird this morning?” one boy whispered.
“Maybe he hit his head,” another said.
Haru, sitting beside Ren, raised a brow. “Oi. Why are you answering like someone’s dad?”
Ren opened his mouth. Closed it. Tried again. “I just thought I should show respect.”
“Respect?” Haru leaned back dramatically. “Bro, last week you were late five times and called the teacher ‘sir’ with a question mark.”
Ren muttered, “Times change.”
Haru squinted. “In one night?”
Ren looked away. “You wouldn’t understand.”
Haru smirked. “Try me.”
Ren remained silent.
Haru’s smirk faded into something softer. Concern peeked through. “Hey. Seriously. Are you okay?”
Ren met his eyes for a brief moment.
No.Absolutely not.Emotionally collapsing.Existentially confused.Temporally displaced.
“Yeah,” Ren lied.
Haru didn’t look convinced, but he didn’t push. That was one thing Ren liked about him. Haru acted like a tornado, but he had decent instincts when it counted.

---
Meanwhile, Yuki struggled through the lesson with the enthusiasm of someone sitting through mandatory training on a Monday morning.
The teacher asked her a simple question.
She blinked. “Sorry, could you repeat that?”
The teacher’s brows shot up. “Yuki-chan, are you feeling alright? You’re usually very focused.”
Yuki forced a smile. “Just a little tired.”
“Tired is fine. But you look… drained.”
Yuki nodded. “Yes. Emotionally.”
The class snickered.
Mina elbowed her. “Why are you talking like someone who works in HR?”
Yuki tapped her notes. “Because I feel like someone who works in HR.”
Mina narrowed her eyes. “Are you hiding something?”
Yuki shook her head. “No. Just tired.”
“You haven’t been this tired since midterms last year.”
Yuki winced. If only Mina knew she’d pulled all-nighters helping kids with homework, arguing with Ren about groceries, and working extra shifts to keep their household running.
“Seriously,” Mina pressed. “You and Ren are acting weird today.”
Yuki froze.Mina noticed.Of course she did.
“What?” Yuki tried to sound normal. Too normal.
Mina leaned closer. “You two didn’t suddenly start dating secretly, did you?”
Yuki nearly choked on air. “No! Absolutely not!”
Behind her, Ren inhaled sharply, as if he’d heard every word.
Haru jumped in from the back. “If they were dating secretly, I’d know. My gossip senses have a fifty-meter radius.”
“Your gossip senses are broken,” Mina shot back.
Haru gasped. “How dare you.”
The two began arguing like always, loud and dramatic.
Yuki exhaled slowly. Saved by the natural disaster known as Haru and Mina.
Still, her nerves stayed tight. Being around Ren felt strangely heavier now. She knew everything he would become, everything they would break, everything they once built together.
A single glance back confirmed it: Ren was staring at her again, eyes thoughtful. Older. Like he couldn’t switch off the part of him that remembered their life.
Dangerous, she thought.This was too easy to fall back into.

---
When lunchtime came, the two of them somehow ended up at the same corner behind the school.
She didn’t plan it.He didn’t plan it.But adulthood had taught them to gravitate toward quiet places.
Ren sat beside her on the steps. Not too close. Not too far.
After a few seconds, he spoke.
“You’re exhausted.”
Yuki nodded. “My brain is thirty. My body is seventeen. That’s not a good combination.”
He let out a dry laugh. “Tell me about it. I tried to drink coffee this morning.”
“And?”
“My mom asked if I was okay because apparently high school me hates coffee.”
Yuki smiled. “You did. You said it tasted like stress.”
Ren looked down. “Some things haven’t changed.”
A quiet moment stretched between them. Not uncomfortable. Just… real.
Ren finally glanced sideways. “Yuki?”
“Yeah?”
“We’re doing a terrible job pretending nothing’s wrong.”
She sighed. “I noticed.”
But neither of them moved away.
And that was the first sign that avoiding each other would be harder than they thought.