Guruma operated as a slave trader in Gesso City, known for his distinctive laugh. Before the nuclear war shattered civilization, he was president of a software company where Siska served as section chief. After the apocalypse, their positions reversed: Siska, now titled "General," seized control by taking Guruma's unnamed young son hostage. This ensured Guruma's obedience and continued involvement in the slave trade.

His primary activity involved capturing people to sell as slaves. During one operation, he captured Yaman and Yaman's family. He also took custody of the severely injured Kenshiro, found after battling wolves. Seeing the slain wolves, Guruma recognized Kenshiro's combat prowess and planned to market him as "The Wolf Slayer."

Guruma's character shifted during Jugai's invasion of Gesso City. He sacrificed his life protecting Kenshiro from attackers. With his dying breath, he implored Kenshiro to rescue his son from Siska, revealing this paternal devotion as his underlying motivation throughout his servitude. Tragically, his son could not be saved, perishing alongside Gesso City's inhabitants during its destruction.