Tsuyoshi Kawabata, a humble convenience store worker in a city near Tokyo, conceals a remarkable secret – he is the unrivaled champion of combat. Reluctant to engage in battles, Tsuyoshi's unmatched skills attract challengers worldwide who seek to best the legendary fighter. However, these hopeful contenders often find themselves swiftly defeated, nursing their wounds discreetly in the convenience store's parking lot. Tsuyoshi imposes three strict rules for those daring to challenge him: a single encounter with no chance for a rematch, a covert location for the fight, and absolute secrecy to be maintained regardless of the outcome.