Gotarō Gō (郷 剛太郎 Gō Gotarō) is Action Mask's alter ego/actor. When not engaged in saving the world, he is a movie stuntman.
In the spin-off manga, Gō takes an undercover mission in Saitama to investigate a series of incidents in which humans are implanted with "seeds" that turn them into monsters through hatred. He transforms into Action Mask to combat the monsters. However instead of attacking the monsters with violence, Action Mask instead tries to reason with them and have the monsters express their feelings, relieving their hatred. This allows the seed of the monster to be exposed allowing Action Mask to use his Action Beam to free the seed from its host.