Masataka Kiyomizu, more commonly known by his alias Kiyomasa, appears as a minor antagonist in Tokyo Revengers. He is a former member of the Tokyo Manji Gang and the leader of his own independent gang during his time as a middle school student. In terms of background, Kiyomasa is a fourteen-year-old student at Shibuya Third Middle School. He is physically imposing for his age, standing tall with a muscular build, black hair styled into a small pompadour, and a noticeable scar over his left eyebrow. His appearance makes him look older than he actually is. He is often seen wearing his school uniform and is known to smoke.

Kiyomasa possesses a cruel and merciless personality. He derives satisfaction from dominating and brutalizing those he perceives as weaker, using violence as a means to assert his superiority. He is highly arrogant and refuses to show deference even to higher-ranking gang leaders, as seen when he initially refuses to bow to Mikey and Draken. When challenged or irritated, he becomes even more vicious, often resorting to weapons like a baseball bat to inflict severe harm. His motivations are primarily driven by a desire for power, control, and the gratification that comes from instilling fear in others. He also holds a vengeful streak, acting out of spite when he feels humiliated.

In the story, Kiyomasa serves as an early obstacle for the protagonist, Takemichi Hanagaki. He is the primary source of Takemichi’s trauma during his middle school years, having treated Takemichi and his friends like slaves. His role is most prominent during the initial arcs, where he operates an underground fighting ring without the consent of the Tokyo Manji Gang. His actions provoke a confrontation with Mikey and Draken, leading to his severe beating and the dismantling of his ring. Later, he is manipulated by others into attempting to kill Draken as an act of revenge for his earlier humiliation.

Key relationships include his subordination to the Tokyo Manji Gang, particularly his antagonism toward Takemichi and his hostility toward Mikey and Draken. He shows little loyalty to any group, acting primarily out of self-interest. Development for Kiyomasa is minimal; he remains a static character whose cruelty and arrogance persist until he is forcibly subdued. He does not undergo a redemption arc or significant change. In terms of notable abilities, Kiyomasa is a capable physical fighter due to his size and strength, but he relies on intimidation and weapons rather than skill. His true strength lies in his ability to control others through fear, though he is ultimately outmatched by the more formidable members of Toman.