Koushirou Kuroki is the founder and head of the Kuroki Detective Agency, a private investigation office in Alkana City. He is an adult male with short gray hair and gray eyes, and his typical attire consists of a light brown trench coat, black pants, a tie, and occasionally a cigarette. Koushirou is a serious-minded individual who often finds himself burdened by responsibilities and blamed for mishaps he did not cause. Despite being the agency’s boss, he does not command much deference from his employees; the three girl detectives who work under him treat the office as their own and sometimes make him the target of their frustrations. He is a longtime friend of Joshua and Artista, two other figures in the city, and these connections root him in the community beyond his professional role. While not deeply involved in the supernatural side of the story, Koushirou provides the cases that send Kotono, Natsuki, and Misaki on their investigative and magical missions, acting as a handler and benefactor. His personality is pragmatic and overworked, and he often serves as a grounded, straight-man presence amid the more eccentric characters. In his spare time, Koushirou enjoys bowling and is genuinely skilled at it, a hobby that reveals a lighter, more relaxed side of his character. He does not display any magical powers or combat abilities of his own, relying instead on his organizational role and the everyday skills of running a detective business. Throughout the series, he remains a reliable if frequently overlooked anchor for the protagonists’ activities.