Originally Tokyo's protector against giant extraterrestrial monsters, UFO-Man defended the city through frequent battles. During one confrontation, he accidentally stepped backwards, crushing and killing three high school girls: Silk Koharuno, Vivienne Ōtori, and Moroboshi Tsubomi. Consumed by guilt, he blamed the monster and resurrected them by transferring a substantial portion of his own power and life energy. This act drastically shrank his body to approximately six inches, rendering him unable to fight monsters at scale.

Post-shrinking, UFO-Man became dependent on a small UFO-like hovercraft for levitation and mobility. He restructured this craft into a wand-like device the girls must grasp to activate their transformations into giant heroines. This device transfers his remaining power to them, though its phallic design and the transformation process—involving him emitting a substance that covers them—carry suggestive undertones. By delegating his power, he effectively drafted the resurrected girls as Tokyo's new protectors.

UFO-Man now operates primarily as the trio's guide and power source. His diminutive size confines him to a supportive role, often observing battles from afar. His personality blends sympathy for the girls' situation with occasional perverse tendencies, including voyeuristic pleasure during their fights. The girls' combat effectiveness is intrinsically tied to his power mechanics; his energy divided among three means their transformations are time-limited and their battle suits deteriorate rapidly. UFO-Man states their strength can be supplemented through intense feelings of humiliation—termed "Moe"—which generates energy when channeled against foes. Despite his reduced stature, he remains invested in their missions, reflecting his lingering responsibility for their condition and Tokyo's safety.