Koji Sugimoto is a Tokyo car mechanic whose routine day is shattered when a military accident spills a prototype powered armor suit, the MADOX-01, into a truck near him. Discovering an operational manual, his curiosity leads him to interact with the suit, triggering a malfunction that traps him inside, preventing escape.

Prioritizing his scheduled meeting with girlfriend Shiori Nagura despite his predicament, Koji navigates Tokyo's urban landscape encased in the conspicuous MADOX-01, attempting ordinary tasks like buying food while evading detection. His movements attract military forces led by Lieutenant Kilgore, who aggressively pursues Koji to reclaim the prototype and settle a personal vendetta against the MADOX system. Forced to defend himself using the suit, Koji gains remote operational guidance from the suit's developer, Eriko Kusumoto.

The pursuit escalates into a direct confrontation within a multi-story parking garage where Shiori waits. Koji, operating the MADOX-01, faces Kilgore in a tank. Following this battle and Kilgore's defeat, Koji successfully meets Shiori as intended. This specific incident represents the character's sole documented appearance across official media.