The City of Sin Academy

The Floating Cloud Sea of the Academy City is renewed every seven years. No one knows that the "perfect graduates" of each class will all vanish under mysterious circumstances three years later.

Gu Ye is assigned to the worst district, the Red Rock Tier, as soon as he enrolls. But he unexpectedly awakens a talent: Echo Perception, which lets him see the emotions and traces left behind in lingering images. His roommates lose their memories one after another, banned drugs are mixed into the cafeteria food, a mentor searches his dorm late at night, and the old library hides a skeleton's final letter... Every clue points to the same answer: beneath this Academy City lies a criminal domain that must never be exposed.

Someone warns him to stop investigating, or he'll die.

Someone else tells him that if he wants the truth, he must rise to the Purple Tier and enter the Forgotten Corridor, sealed behind seven locks.

Gu Ye slaps the clues down on the table. "All I wanted was to be an ordinary student. Now..."

"I'm going to tear a hole in the sky."