The bell rang.
But no one moved.
For a moment, the classroom stayed frozen—like a paused video. Then suddenly, chairs scraped, voices returned, and everything went back to normal.
Except…
"Wasn't there someone sitting there?"
Mina frowned, staring at the empty desk near the window.
Her friend Jisu glanced over.
"Where?"
"There. Third row. By the window."
Jisu shrugged.
"That seat's always been empty."
Mina hesitated.
No… that's not right.
She clearly remembered someone sitting there this morning. A girl. Long black hair. Quiet.
Too quiet.
"Attendance!"
The teacher's voice cut through the chatter.
One by one, names were called.
"Jisu Kim."
"Here."
"Mina Park."
"Here."
The list continued… until the teacher paused.
Just for a second.
Then skipped a line.
Mina's eyes narrowed.
"Sir," she spoke up, "you missed someone."
The class turned toward her.
The teacher blinked.
"Missed… someone?"
"Yes. The student who sits by the window."
Silence.
A few students exchanged confused looks.
"There is no student assigned to that seat," the teacher said flatly.
"But—"
"If you're done, Mina, we'll continue."
His tone wasn't angry.
It was… dismissive.
Like the conversation never mattered.
After class, Mina walked toward the empty desk.
Her footsteps felt louder than usual.
She placed her hand on the surface.
Cold.
Too cold.
Like it hadn't been touched in days.
But that wasn't what made her pull back.
It was the faint carving on the wood.
Words.
Scratched in uneven lines:
"DON'T LET THEM NOTICE YOU."
Mina's breath hitched.
"Hey, what are you doing?"
She turned.
A boy stood by the door, watching her.
He wasn't from her class.
At least… she didn't think so.
"You're new?" Mina asked.
He tilted his head.
"Am I?"
Something about his voice felt off—like he wasn't really asking.
Mina pointed at the desk.
"Do you know who sat here?"
The boy's expression changed.
Not surprised.
Not confused.
Careful.
"You shouldn't ask that," he said quietly.
"Why not?"
He stepped closer.
The air felt heavier.
"Because people who ask that question…"
He looked directly into her eyes.
"…don't stay long enough to remember the answer."
That night.
Mina couldn't sleep.
The words on the desk kept replaying in her mind.
Don't let them notice you.
Who is "them"?
Her phone buzzed.
Unknown number.
A message.
She hesitated… then opened it.
There was no text.
Just a photo.
A classroom.
Her classroom.
Taken from the back.
Students sitting. Teacher at the front.
Everything normal.
Except—
Mina dropped her phone.
In the photo…
The empty seat wasn't empty.
A girl sat there.
Head slightly tilted.
Eyes staring directly at the camera.
At her.
The next morning, Mina rushed to school.
Heart pounding.
She ran into the classroom—
And froze.
The seat was still empty.
But something was different.
Very different.
Her name tag…
was on that desk.
[End of Chapter 1]