Chapter 1: The Black Cage

In the fluorescent-lit classroom of Minamigawa High School, Aria Mizuki sat in the back row by the window, eyes unfocused as her classmates recited lines from a history textbook. She wore the same navy uniform as everyone else, her dark hair neatly tied with a pale blue ribbon, her expression composed and distant. No one ever spoke to her unless necessary. She preferred it that way.

To them, she was quiet. Maybe a little strange, but harmless. Invisible.

That was fine.

None of them knew what she truly was.

The bell rang. Chairs scraped back, students began to chatter and move about. Aria remained seated until the room emptied, eyes still glazed over, her fingertips lightly brushing against the wood grain of her desk. The moment the door clicked shut, her eyes sharpened.

She stood, slinging her school bag over her shoulder, and walked down the hallway with measured grace. Her shoes clicked rhythmically against the floor. She stopped near the janitor's closet. A faint shimmer pulsed in the air. Her fingers traced a symbol in the air, mana flowing from her like water from a cracked dam. A seam split the world open.

Aria stepped through.

---

The Black Cage was quiet. Always quiet.

The walls, if they could be called that, were made of pitch-black stone that absorbed light and sound. Chains hung from every surface, tangled like veins. It was a place removed from space and time, where no god looked and no soul could escape.

A boy hung from the chains, arms suspended above him, ankles bound. His body was already bruised and marked. He couldn’t scream anymore. His voice had given out days ago. But Aria liked the silence. It was honest.

She manifested with a low hum. A ripple in the dark.

Her school uniform shimmered into something more practical: black boots, fitted dark clothing, sleeves rolled to the elbows. She waved her hand, and the room reshaped itself—tools emerging from the walls like flowers blooming in reverse.

Pincers. Hooks. Spikes. Saw-wheels. Instruments no one had ever seen, curved and wicked, their design entirely inhuman. All made of her mana, her will.

"Still alive," she murmured. Her voice was soft, musical.

The boy stirred. Eyes open. Barely.

Aria tilted her head. "That's admirable."

She summoned a thin blade, more like a needle, and drove it slowly into the soft space just beneath his collarbone. No scream. Just the twitch of muscle.

"Pain is fascinating," she said, withdrawing the blade with a twist. "Not for sadism. I don’t enjoy this the way monsters do. I’m just curious. How far can the soul stretch before it snaps?"

She moved slowly, deliberately. Every cut, every tear, was precise. When his breathing slowed too much, she infused just a hint of mana to keep him tethered to life. His body was hers now, until she decided otherwise.

Sometimes she would ask questions. He never answered. That didn’t matter.

She worked for hours. The Black Cage made sure he wouldn’t die until she allowed it. Time passed differently here. She could spend days torturing someone in the span of a single school hour.

Eventually, she paused. She stared at him, head tilted, watching the twitch of his eyelids, the blood staining his skin.

"You're not special," she said quietly. "None of you are."

She raised her hand and with a flick of her fingers, unmade him.

---

Back in the real world, the school rooftop wind tugged at her ribbon. She leaned on the railing, eyes scanning the horizon.

Her mana had grown. Just a little. But it was never enough. Not yet. She could feel it—something beyond the cage, beyond this world, calling to her. Whispering with a voice she couldn’t place. Something buried in obsession.

She didn't understand why she needed to destroy the entity. Only that she must. That truth was bone-deep. Undeniable. Eternal.

The bell rang again. Lunch was over.

She walked down the stairs, expression calm. Her shoes clicked in rhythm. No one greeted her.

Just as she liked it.