Kazuya Mishima, son of wealthy mogul Heihachi Mishima, endures a brutal childhood when his father hurls him off a cliff to test his resilience and nurture darkness within him. He survives by forging a pact with the demonic entity Devil, an act that hardens his heart with vengeance and bitterness. Shaped by years of abuse and manipulation, Kazuya evolves into a ruthless figure consumed by hatred for Heihachi and an unrelenting hunger for power.

As an adult, he enters the King of Iron Fist Tournament to challenge his father and claim control of the Mishima Zaibatsu. There, he crosses paths with Jun Kazama, who witnessed his childhood trauma and seeks to reawaken his buried humanity. Jun’s efforts center on a locket containing a portrait of Kazuya’s late mother—a symbol of his former kindness. Though resistant, Kazuya’s bond with Jun temporarily weakens Devil’s hold, leading him to spare Heihachi and renounce his demonic powers in a fleeting moment of redemption.

Alternate narratives attribute his survival to the Devil Gene, a hereditary mutation from his mother that grants supernatural abilities and ties him inextricably to Devil. After overthrowing Heihachi, Kazuya seizes the Mishima Zaibatsu, only to spiral into corruption through criminal enterprises and genetic experimentation. His later relationship with Jun produces a son, Jin, though Kazuya’s obsession with power persists. Despite repeated deaths and resurrections, he relentlessly pursues dominance, battling Heihachi, Jin, and rivals while striving to perfect his Devil form.

Kazuya’s story oscillates between humanity and demonic sway. Some depictions highlight Jun’s compassion as a catalyst for his brief redemption, while others chart his descent into moral decay. Familial conflicts—particularly with Jin—add layers to his motivations, casting him as both antagonist and tragic product of generations steeped in violence and betrayal.