In 2030, the world was devastated by a sudden attack from unidentified giant biological weapons. The perpetrators, a group of individuals calling themselves Tokoshie, unleashed overwhelming force upon major cities before vanishing without a trace. Eight years later, the remnants of humanity discover that the threat has returned. The stage is set in the fictional city of Ido in Toyama Prefecture, Japan, where the second round of the battle between humankind and the Tokoshie is about to unfold.

The story centers on the reappearance of one particular Tokoshie designated Number 10, who appears on the Shin Minato Bridge. Opposing Number 10 are multiple factions with conflicting goals. The young protagonists Saizaki and Shinako find themselves caught in the conflict, while the mysterious corporation ANASEL pursues its own agenda, seeking to unlock the secret of the Tokoshie’s immortality. A third force, the Anshin Research Organization, also enters the fray, each side carrying its own ambitions and hidden motives.

As a colossal electromagnetic cannon mounted on a monster begins its countdown to fire, the former enemies are forced into an uneasy alliance. Saizaki, Shinako, the Anshin Research Organization, and ANASEL converge on the Shin Minato Bridge, united by a single desperate objective: to stop Tokoshie Number 10 before the weapon discharges and humanity faces total annihilation. The fate of the world rests on the outcome of this final, all-out confrontation.