About
Masaru Aso was the lab assistant of geneticist Doctor Mochizuki, used as one of his experiments related to the creation of the Neonoid, 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.
(Source: Kamen Rider Wiki)
