Masaru Aso was the lab assistant of geneticist Doctor Mochizuki, used as one of his experiments related the creation of the Neo Organism, enabling him to transform into a grasshopper-like being called Kamen Rider ZO. He fled into the mountainside and went into a coma before he was awakened by a telepathic call two years later with an unconscious urge to protect Hiroshi Mochizuki, the son of Doctor Mochizuki.
Hiroshi Tsuchikado
Masaru Asou / Kamen Rider ZO
Isao Sasaki
Doctor Mochizuki
Shohei Shibata
Hiroshi Mochizuki
Hiroshi Inuzuka
Seikichi Mochizuki
Naomi Morinaga
Reiko
Kenji Ohba
Kuroda
Masaru Yamashita
Nishimura
Iori Sakakibara
Miyazaki
