Toshiaki Gozu, known as Gozu, emerged from a troubled upbringing under parents who forbade him from playing games, leaving him to watch others play during cram school. He earned rare parental praise for scoring 82 on an exam, but his home life grew unbearable, culminating in him striking his father and fleeing. He then lived recklessly among dangerous individuals who paid for his companionship, which he leveraged for survival and connections.

His life ended when he was shot and killed, after which he awakened in a fantasy world he recognized from a video game he had been fascinated with in childhood. Reincarnated as a background assassin, his assigned mission was to kill the demon king Evelogia. Upon meeting him, however, Gozu felt an immediate, profound connection, having idolized the character since youth. Thrilled by the encounter, he abandoned his task and chose instead to protect Evelogia, whom he saw as his only true inspiration.

Gozu exhibits a bold, aggressive, and reckless nature, showing little fear toward violence or pain. His most defining trait is an unwavering devotion to Evelogia, expressed through exuberant support and a determination to prevent the original game storyline in which Evelogia is slain by a hero. Using his knowledge of the game’s events and strategies, he works to alter these fated outcomes.

A pronounced masochistic and lustful dimension defines much of his behavior. He expresses desire to be harmed by Evelogia, claiming it would feel great to die by his hand. He openly engages in intimate acts with Evelogia, regardless of onlookers, and speaks freely about his wishes, including a desire to be impregnated by him.

His worldview is cynical, especially concerning love and heroism. He resents the game’s hero, who claimed to act for the world yet saw no issue in killing the demon king. He criticizes using love to justify deception, violation, and murder, and once cynically advised a sacrificial bride to sell her body rather than await death.

After reincarnation, his sole purpose becomes ensuring Evelogia’s survival and happiness. He strives to rewrite the story to prevent Evelogia’s death, taking actions such as securing a jewel in ruins before the hero can claim it. He also expresses desire to conquer or destroy the world alongside Evelogia, referring to it as a pre-wedding vacation. Though adaptable, he faces challenges like being unable to read the world’s written language despite understanding its speech.

His relationship with Evelogia is the core of his existence. He is fiercely protective, physically affectionate, and swiftly confesses his love. He urges Evelogia to be more assertive and to cease constant apologizing. His loyalty is absolute; he declares he will allow no one—not the hero nor his companions—to stand in Evelogia’s way. He is described as Evelogia’s first and only choice, and the first person to genuinely protect him.

He interacts with others primarily through the lens of protecting Evelogia, confronting the demon king’s parents over their treatment of their son and reacting angrily to townspeople who speak ill of Evelogia. His game knowledge leads him to suggest taking the sacrificial bride Tishia along to save her, as occurs in the game, though he later shows jealousy when others display affection toward Evelogia.