Minoru Kanuma is a member of Shishitoren, also referred to as the Shishigashira Union, one of the rival delinquent groups in the story. He is a seventeen-year-old teenager of average height, standing approximately one hundred and seventy centimeters, with a lean build weighing about sixty-four kilograms. His black hair is tied back into a neat bun, with the sides of his head shaved, a style that gives him a slightly quirky yet deliberate appearance. He typically wears the Shishitoren jumper over a black hoodie and often carries a bitter or exasperated expression, especially when irritated.

Born on September third, Kanuma presents a layered and somewhat contradictory personality. On the surface, he comes across as arrogant, smug, and violent, embodying the stereotypical aggressive demeanor of Shishitoren. He is easily irritated and quick to anger, especially when insulted or ridiculed, and he has a notable lack of empathy for others. However, underneath this tough exterior, he is actually timid, anxious, and childlike for his age. He can become a nervous wreck when things do not go his way and tends to put his hands over his mouth while speaking in a childish manner. He also has a fondness for cute things, though he tries to appear more manly to compensate, such as maintaining his hair in a bun.

Kanuma's motivations are closely tied to his relationship with Yukinari Arima, whom he has known since childhood. Arima is an important figure and close friend to him, and the two are frequently seen together, operating almost like brothers. Kanuma looks up to Arima and is very defensive of him, showing a loyalty and care that stands in stark contrast to his otherwise cold treatment of others. Within the group, he values power and status, but his sense of self-worth is heavily dependent on Arima's approval and presence.

In the story, Kanuma serves as a supporting antagonist and a member of Shishitoren's ranks. His role is relatively minor compared to the group's leaders, but he is still more experienced and physically capable than an average street fighter. Despite this, his combat skills are not particularly remarkable. He relies on physical aggression and a bullys demeanor rather than technique or discipline. In a one-on-one fight against Hayato Suo, he was easily outmatched, unable to land a single hit and left stumbling without any effective defense or strategy. This defeat exposed his lack of true fighting ability and his tendency to crumble under pressure when his usual intimidation tactics fail.

His relationship with Arima is the most significant connection in his life. The two are inseparable, and Kanuma often mirrors Arima's aggressive tendencies. Beyond this bond, he shows little regard for others, displaying cruelty and a bullying nature without hesitation. He has been shown chasing down middle schoolers for sport and mocking his own teammates when they lose. His lack of empathy is cited by Suo as the fundamental reason he lacks true strength, as his aggression is not backed by genuine resolve or skill.

Kanuma does not undergo significant development within the early parts of the story. His defeat at the hands of Suo humbles him in the moment, but his core personality remains largely unchanged. He continues to act as an extension of Arima within Shishitoren, and his role remains that of a loyal but ultimately outmatched follower rather than a leader or major threat. His behavior and mannerisms, including his childish speech and nervous habits, make him stand out among the more imposing members of his group, revealing a character who uses bravado to mask deep-seated insecurity.