Fumio Fukamachi (深町 史雄 Fukamachi Fumio) is a widower and Shō's father, but almost nothing else is known about him. He is captured and used by Kronos as a guinea pig and turned into the Anti-Guyver Zoanoid Enzyme II to entrap Shō. Under Dr. Barcas' telepathic control, he nearly kills Sho, almost crushing his skull and resulting in the Guyver's own intelligence taking over his body. Recognizing only an obvious threat the Guyver ruthlessly slaughters Sho's father. This results in a mental block that prevents Sho from transforming until Aptom tells Sho of his father's fate.
Fumio is a hard-working salaryman, a widower who lost his wife to as-yet unknown - but presumably mundane - circumstances, and the father of the main character in Guyver.