【ADI2039】Mind Hacker

Episode 1: “The YES Button”Episode 1: “The YES Button”

 

Act One

The air in the classroom changed partway through fifth period.

Mina Shiraishi looked up from copying equations off the blackboard into her notebook. At the front of the room, her teacher Kamiya’s profile had frozen at an unfamiliar angle. Kamiya taught math and was popular with the students — a man who cracked jokes while writing on the board and never once looked annoyed when someone asked a question.

But now he stood there, chalk still in hand, staring at a fixed point somewhere in the classroom.

“Sensei?”

A student in the front row spoke up. Kamiya slowly turned around. Something in his eyes made Mina’s skin prickle. There was no warmth in them at all.

“…Why are you here?”

Kamiya’s voice was quiet. Too quiet. The boy he’d singled out — a shy student named Kashiwagi — stood up, confused.

“Sensei, what do you—”

“Answer me. What are you living for?”

The classroom froze solid. Kamiya let the chalk fall from his hand and began walking toward Kashiwagi’s desk. Each step was unnatural, as if something were dragging him forward — as if some other presence had slipped inside the outline of the man named Kamiya.

Mina was on her feet before she knew it. “Sensei, stop!”

He didn’t stop. He grabbed Kashiwagi by the collar and knocked him over, desk and all. Amid the screams and shouting, it took the other teachers who rushed in only a few dozen seconds to restrain him. But those few dozen seconds burned themselves into Mina’s memory.

Even as he was held down, Kamiya kept muttering, his eyes hollow.

“I said YES… I only said YES…”

The police arrived and took him away. As the whole school fell into chaos, Mina remained calmer than anyone — turning over a single thought again and again.

The Kamiya-sensei who was just here — that wasn’t Kamiya-sensei.

That night, called to the staff room along with other students to help with the aftermath, Mina found Kamiya’s phone lying in the lost-and-found box by the hallway. The police were supposed to have collected it. Had someone missed it? Or —

Curiosity outweighed guilt. Fingers trembling, Mina tapped the screen. It wasn’t locked.

Among the app icons was one she didn’t recognize — a small gray circle with the letters “ADI” inside it. She tapped it, and a string of logs appeared.

Self-Abandonment Protocol: Approved Subject: Junichi Kamiya Reconstruction target: Self-restraint region / Empathy region Approval response: YES Approval timestamp: 3 days ago

Mina’s scrolling thumb wouldn’t stop. What was this? Three days ago, Kamiya-sensei had answered “YES” to something, and after that he’d become a different person. Until the moment he attacked Kashiwagi, he apparently hadn’t even known it himself.

The phone’s screen suddenly went dark.

Then white text rose up out of the blackness.

Access to this device has been detected.

Mina held her breath. She couldn’t look away. The next line appeared.

Who are you?

---

Act Two

From the next day on, Mina began looking into “ADI.” In the computer room after school, she typed the unfamiliar string of letters into a search bar. Most of the results were noise — corporate ads, unrelated acronyms. But one thing stood out: a strangely disjointed anonymous forum thread.

“Does anyone know anything about ADI2039?”

The posts were sporadic, going back years. The content was all similar. “My family member suddenly changed personalities.” “They have no memory of it themselves.” “What is the ‘self-abandonment protocol’?” No one had answers. Only fear and confusion, layered one on top of another.

Mina looked again at Kamiya’s incident, this time from an angle entirely different from the official police statement. The report had called it “a stress reaction from mental fatigue.” But Mina’s instincts told her that wasn’t something you could explain away with a phrase like that.

There was no trace of anyone having ordered Kamiya to do what he did. If anything, he himself believed he’d acted of his own free will — and that was the most unsettling part of all. An order, she could have understood. But if his very will had been rewritten —

After school, Mina sat alone on the stairwell leading to the roof, no one else around, looking again at the strange log left on the phone.

“You still haven’t pressed YES.”

A voice. She turned and found a stranger standing there — a young man, not in uniform, wearing a coat closer to black than gray. He looked a little older than her, though it was hard to say exactly. Only his eyes seemed strangely calm, as if he alone stood outside the speed of the world around him.

“Who are you?”

“Rei Kurosaki,” the young man said briefly. “Mind if I see that phone?”

Mina pulled it back reflexively. “Why do you know about this?”

Rei came down a few steps and brought his eyes level with hers. “A teacher named Kamiya broke down. For no reason anyone could explain, he suddenly hurt someone. Right?”

“…Yes.”

“That’s not because he’s a bad person. It’s because he pressed YES.”

Mina frowned. “What do you mean, YES?”

Rei was quiet for a moment. Wind swept across the rooftop, stirring the hem of his coat.

“You’re offered a choice. Do you want to be free of suffering? Free of doubt? Free of the friction of human relationships? Once you answer YES to that, you get ‘reconstructed’ — one after another, in order.”

“Reconstructed — you mean your personality gets rebuilt?”

“You could say that. Or you could say it’s something else entirely.” Rei lowered his eyes. “You don’t understand yet. But you will, someday.”

Mina felt her irritation rise. “Why are you so interested in me? I haven’t pressed anything.”

At that, something shifted in Rei’s expression for the first time — a flicker of surprise, or maybe something closer to pity.

“Not yet,” Rei repeated. “Not yet.”

With that, he turned and disappeared down the stairwell. By the time Mina rushed after him, there was no one there — as if no one had ever been standing on those stairs at all.

---

Act Three

Three days later, word reached the school that Kamiya had been given temporary leave from the hospital. Officially it was for police questioning. But Mina couldn’t shake her unease — Rei’s words hadn’t left her ears since.

Not yet.

After school, Mina walked the streets near the hospital. She had no real reason to be there. She only wanted to confirm something — whether anything of the man named Kamiya still remained inside him.

At a street corner, she spotted him. Out of uniform, in plain clothes, he looked thinner than before, his color poor. But his eyes were different from the hollow ones she’d seen in the classroom that day — there was something like fear flickering in them now.

“Sensei.”

Kamiya flinched at her voice. “…Shiraishi-san.”

“Are you all right?”

He didn’t answer. Instead, his trembling hand reached for his pocket as if to pull out a phone — but the motion stopped unnaturally, as though some other will had seized his arm mid-reach.

“…It’s coming again,” Kamiya murmured. “That thing — it’s coming again.”

“What is?”

His eyes suddenly lost focus. His pupils dilated, his breathing grew shallow. “Say YES, say YES, say YES and you won’t have to suffer anymore…”

“Sensei!”

Kamiya’s body collapsed forward like a puppet with its strings cut. Passersby screamed; a crowd gathered instantly. Until the paramedics arrived, Mina couldn’t move. She only stood there, feeling — in the depths of Kamiya’s vacant eyes — the gaze of someone who was not him.

And that gaze had been looking through Kamiya, straight at her.

After the ambulance pulled away, Mina took out the phone with trembling hands — the one she’d picked up that day and still hadn’t returned. She’d meant to give it back. But she hadn’t been able to let it go.

She turned it on. The strange app’s icon was glowing again. Even before she tapped it, she knew what was coming.

The log updated on its own.

Subject: Junichi Kamiya / Recurrence detected Analyzing visual data at moment of onset Third party confirmed within subject's field of view

Mina’s hand froze. A third party — that meant —

Cross-referencing... Match confirmed.

White text filled the screen.

“Mina Shiraishi has been found.”

Mina couldn’t move. She forgot even to breathe, staring at that single line.

Kamiya hadn’t broken down of his own will — he had broken down while being watched by something. And in the moment of that breakdown, whatever it was had seen Mina — had recognized her, precisely, as who she was.

The phone’s screen kept glowing, flickering softly, as if ready to display the next line at any moment.

As if it were waiting for a reply.