Ren doesn't sleep much.

Nightmares drag him back to a world he can't forget.

At Seiryo University, he passes as just another student—until the day his classmates turn violent and the city collapses into chaos. Trapped in a quarantined zone overrun by the infected, Ren is forced into a role he swore he'd never take again. But saving others means exposing who he truly is... and the past that refuses to stay dead.