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.

• Ishimori Productions
• Toei Company
• Hiroshi Tsuchikado
• Isao Sasaki
• Shohei Shibata
• Hiroshi Inuzuka
• Naomi Morinaga
• Kenji Ohba
• Masaru Yamashita
• Iori Sakakibara