Aptom is a battle creature who was a member of the Lost Unit, a commando squad consisting of Aptom as leader, Somlum, and Dyme. These three were quite fond of one another, as they shared hardships of being Lost Numbers and being mocked by Zoanoids which they worked while the Hyper Zoanoids would hold them with great contempt. Aptom's compatriots were killed in a battle against Sho Fukamachi AKA Guyver 1. Aptom then became hellbent on killing Guyver 1 himself, even to the point where he would ally himself with his nemesis against a threat that would possibly end them both alone.
Aptom has contemplated taking up wrestling, seeking to prove himself as the ultimate battle creature.