One assassin. One virus. One chance to stop the end of humanity.Five years ago, Ry¿ killed his Yakuza partner Niko-after watching him murder the woman he loved.Now living as Hiroshi Ichihara, a quiet college student, he's buried his past. A second chance. A normal life.Until a first date shatters everything.Forced to reveal himself, Ry¿ discovers the impossible: Niko is alive.Worse, he's united the Yakuza clans and engineered a CRISPR virus that could destroy the world. Only one person can stop him-the assassin Ry¿ swore he'd never become again.But there's a price. Every kill awakens the darkness inside him, the bloodlust that made him Tokyo's most feared killer. The more he fights, the more his humanity slips away.With Ayako Yanagi-a brilliant doctor caught in the crossfire-as his only ally, Ry¿ must return to Tokyo's underworld to infiltrate Niko's genetically enhanced army and stop the virus before it's unleashed. But defeating his former brother-in-arms may cost him the one thing he's fought to keep: his soul.Can he save the world without becoming the monster he fears most?