Ken, a knife-throwing prodigy, infiltrates a shadowy thief syndicate under a enigmatic leader. Tasked with executions during high-stakes heists, he forges an unexpected bond with a girl dubbed Chiko, imparting his lethal craft while bestowing the affectionate nickname. Their rapport evolves into a sibling-like bond, with Chiko dubbing him "big brother."

A catastrophic train accident engineered by their rivals leaves Ken with a shattered left eye and the presumed annihilation of the group. Surviving with Chiko, his fractured psyche unravels, haunted by abandonment after interpreting the leader’s preferential treatment of Chiko. This betrayal brews a ruthless edge that dictates his choices.

In a climactic train showdown, Ken thwarts Chiko’s attempt to rescue a foe, embodying his hardened worldview. His unwavering allegiance to the syndicate and volatile kinship with Chiko anchor his journey, underscoring narratives of survival, vengeance, and fractured morality within a labyrinth of crumbling loyalties.