Kamo Serizawa is a significant secondary character in the narrative, depicted as a member of the Miburo. He serves as the group's first lead commander and is a figure who is both brutal and strategically cunning. His background is firmly rooted in his historical counterpart, presented as an individual whose actions leave a deep and often troubling mark on the organization before it transforms into the Shinsengumi.

In terms of personality, Serizawa is portrayed as brash, violent, and quick-tempered, with a reputation for erratic and ruthless behavior. He is an imposing figure who seems to enjoy demonstrating his power, often through acts of cruelty that instill fear in those around him. A distinct aspect of his character is his tendency toward drunken rages and destructive acts, which contribute to the Miburo’s notoriety. Despite this volatile exterior, he possesses a sharp and perceptive mind. He is shown to be good at reading the emotions of others, manipulating them to serve his purposes. Serizawa’s motivations appear to be driven by a personal philosophy where playing the role of a villain is a necessary tool for achieving his larger goals. He believes in decisive, brutal action and lacks patience for what he perceives as softness or a lack of resolve in others.

Within the story, Serizawa’s role is central to establishing the morally ambiguous atmosphere of the Miburo. He is a source of internal conflict, responsible for purging members of his own group whom he considers threats. An early example of this involves a fellow member named Toroichi, whom Serizawa kills after discovering his plans to betray the Miburo. While he publicly frames the killing as a random act of drunken violence, it is understood to be a calculated execution, demonstrating his willingness to do whatever it takes to protect the group from within, regardless of the moral cost. His leadership style is characterized by a combination of strategic mastery—securing resources and alliances—and chaotic, alienating violence that jeopardizes the group’s external support.

Key relationships highlight his controlling and abusive nature. He has a servant or attendant named Taro, who essentially acts as Serizawa’s personal punching bag, enduring beatings and being ordered to clean up the aftermath of his violent acts. While Taro seems to accept this harsh existence out of gratitude for having basic needs met, other members like Hijikata and Okita warn the protagonist to stay away from both Serizawa and his servant, indicating the danger that surrounds him. Another notable ability is his skill in reading people, allowing him to manipulate others effectively, such as when he uncovers a plot against a fellow leader. Regarding his development, the story hints at hidden depths, as his violent purge of a traitor suggests a strategic mind working beneath the surface of his drunken rages, though he denies any premeditation.