Kyousuke Irie directs the Irie Clinic in Hinamizawa, a facility functioning as a front for "Tokyo's" research into Hinamizawa Syndrome. While nominally in charge, actual authority rests with Takano Miyo, as "Tokyo" preferred a male figurehead. Irie accepts this arrangement, aware his role includes becoming a scapegoat if operations fail; this leads to his suicide by sleeping pill overdose in tragic timelines like Tatarigoroshi-hen and Minagoroshi-hen to avoid government arrest. Born into poverty, Irie aspired to become a doctor from childhood, earning local renown as "Doctor Kyōsuke-kun." Acceptance into a prestigious Tokyo medical school prompted his parents to host an expensive celebration. During his studies, his father developed violent outbursts due to an organic brain syndrome from a construction injury. After his father's death in a street fight, Irie specialized in neurosurgery, focusing on psychosurgery to address conditions like his father's. He gained notoriety for successful lobotomies, continuing the practice illegally after its ban, resulting in his expulsion from the medical community. This attracted "Tokyo," leading to his recruitment into Takano’s research group. Irie is tall with light brown hair parted in the middle, green eyes, and distinctive oval glasses. He typically wears a black vest, gray shirt, yellow tie, and lab coat at the clinic. His casual attire includes a yellow shirt and white pants. As coach of the Hinamizawa Fighters baseball team, he dons a red-white-yellow uniform. His relationships are complex, particularly with the Hōjō siblings. He administers regular injections to suppress Satoko's Hinamizawa Syndrome symptoms and has expressed a half-joking desire to marry her, often gifting her maid accessories reflecting his fetish. Despite once considering dissecting Rika Furude for research, her influence redirected his focus toward developing a cure. He concealed Satoshi Hōjō’s condition after the boy succumbed to terminal-stage Hinamizawa Syndrome in 1982, placing him in a pharmacological coma in the clinic’s basement and caring for him indefinitely while contributing research toward Satoko’s treatment. With Takano, Irie maintains a professionally subordinate yet morally conflicted dynamic. Unaware of her orchestration of tragedies in most timelines, he collaborates on dissections of Syndrome patients, including vivisecting a construction manager. He later aids Rika in thwarting Takano’s plans in Matsuribayashi-hen after learning her true intentions. His interactions with Tomitake Jirō appear cordial, lacking suspicion about Takano’s role in Tomitake’s deaths. His actions across story arcs reveal ethical tensions. In Tatarigoroshi-hen, he initially believes Keiichi’s murder confession but later deems him delusional, inadvertently enabling Keiichi’s escape. During the Watanagashi Festival, he identifies Satoshi’s murdered aunt but lies to authorities. In Minagoroshi-hen, he supports protests against child protective services to protect Satoko and calms her breakdowns with injections. His development peaks in Matsuribayashi-hen, where he collaborates with Rika’s group to prevent disaster. In later continuations like Rei, Irie remains active in village affairs 35 years after the original events. In Gou and Sotsu, his role expands under duress: coerced by an adult Satoko, he administers the H-173 pathogen to Rika to reintegrate her into the loops, highlighting his ongoing vulnerability to manipulation.