Makoto Moroboshi serves as Tsubomi Moroboshi's older brother and an active photographer in his high school press club. He relentlessly chances to photograph the city's giant heroines, the Ultimate Girls, spurred by monetary rewards for uncovering their civilian identities. This fixation fuels his persistent involvement across events.

He cultivates romantic feelings toward Silk Koharuno, one of the Ultimate Girls, layering personal stakes atop his pursuits. This infatuation sparks a downward spiral when he inadvertently fuses with an alien green slime in the series' final episodes. The merger corrupts him into a dark incarnation of UFO-Man, consumed solely by exposing Silk's secret identity and annihilating her.

The slime's influence entirely overrides his original personality, forging an entity fixated on destruction. This metamorphosis shifts his role from a peripheral supporter to the central antagonist driving the climactic conflict.