Saburo Kazeda, a junior high school student nicknamed Sabu, is an orphan adopted by a fishmonger and his wife. He grows up unaware that he is a mutant with powerful psychic abilities. His life changes when he receives a telepathic call from a girl named Rion, a member of the Shonen Domei, a group of young espers dedicated to protecting humanity. Rion explains that a self-proclaimed mutant king named Banba believes the emergence of paranormal humans signals a natural selection that will replace ordinary people with a new mutant race, the Neo-Human Empire. Banba’s forces are already attacking and eliminating humans as well as any mutants who oppose him.

At first Sabu is skeptical, but when he discovers that his own teacher is a mutant working for Banba and trying to kill him, he joins the Shonen Domei. With the help of Commander Sarra, he learns to harness his powers. Sabu can transform in two stages: first into a pupa-like creature called Sanagiman by concentrating energy and shouting “Gōriki Shōrai.” In this armored brown larval form, he can absorb kinetic energy from enemy attacks. Once he gathers enough energy in his belt, he triggers a second transformation by shouting “Chōriki Shōrai,” causing the Sanagiman shell to explode and reveal his true form: Inazuman, a blue moth-like humanoid with lightning-shaped antennas, a yellow scarf that can become various weapons, and the ability to fight with superhuman speed and strength.

The manga follows Sabu and his allies in the Shonen Domei as they battle Banba’s mutant minions and the Neo-Human Empire’s schemes. Notable narrative arcs include the initial awakening and recruitment, the betrayal by Sabu’s teacher, confrontations with new types of mutant enemies, and the story “The Boy with a Guitar,” where Sabu faces the android Kikaider in a crossover that ties into Ishinomori’s wider universe. The series is a hard science‑fiction story centered on psychic boys fighting a grand-scale war for the survival of the human race.