Michael Marsh, a 13-year-old middle-class student, finds his ordinary life upended after Jumbow—his humble school-commuting robot—is transformed into the battle machine Galatt by an enigmatic scientist. Forced to pilot the weaponized robot under threats of legal retaliation for its illegal modifications, Michael dons protective goggles and an overall suit to mask his identity during covert missions.

His father’s stable corporate job anchors a predictable family life, contrasting sharply with Michael’s secret role defending Earth from alien forces. Initially driven by fear of punishment, he reluctantly engages in combat, unaware his actions secretly fund the scientist’s shady ventures. Mocked by classmates for Jumbow’s obsolete design—a flaw the scientist weaponizes to manipulate him—Michael begrudgingly allies with peers Patty and Kamil, fellow pilots of Galatt units.

Through clashes with extraterrestrial threats and uneasy alliances, his hotheaded demeanor slowly matures into a tempered resolve. Interactions with allies and enemies alike sharpen his tactical instincts and sense of duty, even as he balances the dual burdens of secrecy and survival.