When one of Ayumu's teachers promises to give him a few clues about the Blade Children, the deceptively cute Rio, one of the Blade Children herself, ruthlessly murders the man in broad daylight. Faced with another brutal murder to solve and one step closer to finding out what the Blade Children really are, Ayumu and Hiyono find themselves the direct targets of Rio's malice. When her murderous plot backfires and Rio finds herself in the hospital, she challenges the visiting Ayumu to a life-and-death gamble, only to find herself face-to-face with Hiyono, who call's Rio's bet and raises her one!

Ayumu Narumi aggressively pursues his goal to unravel the mystery of the "Blade Children." With every step he takes, though, the path to the truth becomes more treacherous as a conspiracy is revealed. Could it be that Ayumu's fate was intertwined with that of the Blade Children even before his journey began?