Kyôsuke Irie directs the Irie Clinic, Hinamizawa's only medical facility, and manages the Hinamizawa Fighters baseball team. Appearing in his late 30s to early 40s, he has short hair and wears glasses. His work attire typically consists of a lab coat over a black shirt and yellow tie, while his casual wear includes a yellow shirt, white pants, and blue shoes. His impoverished childhood fueled his ambition to become a doctor. Witnessing his father's violent outbursts, later traced to frontal lobe trauma from a construction injury, sparked his interest in neuroscience. Excelling in medical school, he specialized in psychosurgery and gained recognition as a "young genius" for successful lobotomies. Expulsion from the medical community followed his continued performance of unauthorized lobotomies after the practice was banned. Recruited by the secret organization Tokyo for his expertise, Irie moved to Hinamizawa to research Hinamizawa Syndrome under Miyo Takano. The Irie Clinic served as a front for this research, with Irie as the public director while Takano held de facto control. Tokyo positioned him as a scapegoat if operations failed, requiring his approval of Emergency Manual #34—a contingency plan for exterminating all villagers. In timelines where this occurred, Irie typically committed suicide via sleeping pill overdose to evade arrest. Irie treats Satoko Houjou for advanced Hinamizawa Syndrome, administering regular injections to suppress symptoms. Despite his eccentric fixation on making her wear maid outfits and joking about marriage, he genuinely cares for her well-being and wishes to adopt her, though legal restrictions prevent this. He saved her brother, Satoshi, after Satoshi developed terminal symptoms in 1982, placing him in a pharmacological coma in the clinic's basement while seeking a cure. His research on both siblings significantly advanced understanding of the syndrome. His relationship with Takano is complex. Initially trusting her as a colleague, he later uncovered her role in orchestrating murders and dissections, including those of Rika Furude's parents. Though complicit in some unethical acts—such as vivisecting a terminal patient at Takano's urging—he persuaded her to allow experimental treatments for Satoshi and Satoko instead of dissection. In Matsuribayashi-hen, after learning of Takano's plan to trigger the Great Hinamizawa Disaster, he allied with Rika to stop her. His actions vary across timelines. In Tatarigoroshi-hen, he initially believed Keiichi Maebara's confession of murdering Teppei Houjou but later dismissed it as delusion. Following Takano's alleged death, he vowed to prevent the curse's spread but was found dead from suicide days later. In Minagoroshi-hen, he supported protests against child protective services to protect Satoko from abuse and helped calm her during a breakdown with medication. His involvement culminated in Matsuribayashi-hen, where his past and research were fully revealed as he aided in confronting Takano. In the sequel Rei, set 35 years after the original events, Irie remains in Hinamizawa and participates in town meetings, indicating his continued residence and community involvement.