The first thing he noticed was the ceiling.
Not his ceiling. Not the cracked-off white panels of his cheap apartment. Not the glow-in-the-dark stickers he put up when he was drunk or the spider that made its kingdom above the window.
This was wood. Dark, polished, unfamiliar wood. Old-fashioned. Japanese.
The second thing he noticed was the smell—tatami mats, fresh air, maybe a hint of incense. It wasn't unpleasant. But it wasn't his. He sat up too quickly, a pounding headache instantly reminding him that something was very wrong.
And then he saw the letter.
Folded cleanly, square, resting on the small table in front of him.
No name. No seal. Just plain white paper. His hand moved on its own, hesitant fingers brushing the edge before he picked it up and read:
"Hello world. If you're reading this, you're in the world of JJK. This is before the 0 movie, so nothing has happened yet. Do what you will."
He blinked.
Then blinked again.
Then whispered: "…What the fuck?"
He stood up—well, tried to—but his legs gave out like wet noodles, and he collapsed back onto the tatami. He looked down at his hands. Slender. Pale. Not the same little scar near the thumb. Not his hands.
"No. No no no no no. This isn't funny."
He scrambled to his feet again, this time succeeding, and rushed to the mirror hanging above a wooden dresser.
The face that stared back wasn't his.
Sharp cheekbones. Slightly long black hair, the kind that curled in humid weather. Deep brown eyes. A youthful, almost delicate jawline. Definitely younger than he'd been before.
Panic hit him like a freight train.
He reeled backward, slamming into the dresser. "What the actual—where the fuck am I?! What is this, some kind of isekai?! Some goddamn SAO-type shit—no, no, no, this isn't real!"
He spun back toward the note, reading it again. "JJK… world… before the 0 movie…"
And that's when it clicked.
"Jujutsu Kaisen? Jujutsu fucking Kaisen?! You've got to be kidding me."
His knees buckled. He dropped to the floor. "Oh my god. Oh my fucking god."
His brain whirled through memories—the manga, the anime, the lore. He'd read the manga at least three times. He hated how it ended. Hated how everyone died, how it all spiraled into that damn death spiral. He was just a nerd, a manga reader, a guy who liked his stories not to end in nihilism.
And now he was in that world.
"Shit, shit, SHIT!" He ran his fingers through his unfamiliar hair. "Why? WHY? God? Is this a punishment?! I didn't even do anything! I wasn't even religious! What the hell, man!"
He looked around the room again, heart still hammering.
No tech. No phone. No wallet. No ID.
Wait.
A schoolbag sat in the corner. Plain black canvas. He stumbled to it, rummaging through with clumsy hands.
Notebooks. Pens. A student ID.
He squinted. The kanji wasn't foreign to him—thankfully his host's body seemed to know Japanese—but it still took a second to read.
"Ren… Sato. Student ID #22118. Tokyo Prefectural High School."
"Ren Sato…" he repeated, the name tasting strange in his mouth.
"So that's who I am now."
He let out a bitter laugh, half-mad and half-despairing. "Okay. Okay, sure. Just drop me into a cursed-infested world with nothing but plot knowledge and the name of a nobody side character—*"Who the hell is Ren Sato?!"*
He didn't remember any Ren Sato in the manga.
Not in the main cast. Not even among the Kyoto students.
A nobody.
He was a nobody in a cursed world.
No technique. No cursed energy (as far as he knew). No Gojo Satoru deus ex machina protecting his dumb ass.
Just him. And the knowledge of how everything will go down.
"Fuck you, God," he said to the ceiling. "Seriously. Fuck you."
But deep down, even in the middle of his terror, a thought itched in the back of his mind.
If this really was before JJK 0…
Then nothing had happened yet.
Suguru Geto was still out there, planning. Gojo was still Gojo. Yuji hadn't eaten Sukuna's finger. Mahito was probably crawling out of the primordial soup somewhere.
This was a reset. The calm before the apocalypse.
And he was here.
Alive. Early.
Maybe—just maybe—he could do something about it.
But that thought was for tomorrow.
Right now, he needed to get through the day without being eaten by a curse.
Or worse—mistaken for a sorcerer.
He fell back onto the tatami mat and stared at the ceiling again.
"Okay," he muttered. "Ren Sato. High school student. JJK world. Don't die. Don't mess with the timeline. Try not to lose your shit again."
He closed his eyes.