Gekko Itabashi is a male character with blonde hair who exhibits a flamboyant and theatrical personality during a school infiltration sequence. His behavior displays classic "Chuunibyou" traits—characterized by delusional self-perceptions, grandiose beliefs in hidden powers, and overtly exaggerated, attention-seeking mannerisms.

After receiving an SCM device from his online acquaintance Maria, Gekko enters the SCM system, a series of enslavement games central to the narrative. He later forms an alliance with Maria and Kiyo, an alternate personality emerging from the character Zero. This trio or quartet had already established cooperative collaboration for an unspecified duration prior to their on-screen appearance. Their alliance follows Kiyo's escape from the control of Ryuuo.