Mitsuo Suwa, a lazy young boy, encounters Birdman, an alien belonging to a group that maintains peace in the galaxy. Birdman recruits Mitsuo to become a Perman. Mitsuo receives three items: a helmet that multiplies the wearer's physical strength and serves as a mask, a cape that allows the wearer to fly and run with great speed, and a badge that enables the wearer to breathe underwater and communicate with Permans. Birdman instructs Mitsuo that if a Perman's identity becomes known to others, his brain will be destroyed—which is reduced to being turned into an animal. To help keep Mitsuo's secret identity, Birdman will give Mitsuo a doppelgänger robot called a copy-robot, who takes Mitsuo's place when Mitsuo is on duty as Perman. During his duty as Perman, Mitsuo meets other Permans; Booby, Perko and Peryan, and they soon become best friends. Perman's story later revolves around the bonding between the Permans and their adventures of averting crime and disasters.