OVA
Description
Kyosuke Irie directs the Irie Clinic in Hinamizawa. His impoverished childhood fueled a desire to become a doctor, intensified by witnessing his construction worker father's violent outbursts – later diagnosed as organic brain syndrome from a head injury. This experience drove Irie to specialize in neurosurgery and psychosurgery, convinced mental illness originated from physical brain disorders.

Gaining acclaim as a "young genius" for successful lobotomies, Irie persisted with the banned procedure without patient consent, leading to his expulsion from the medical academic community. This exile resulted in recruitment by the secret organization "Tokyo," which installed him as director of the Irie Clinic – a front for researching Hinamizawa Syndrome. While nominally in charge, true authority resided with researcher Miyo Takano; Irie functioned as a figurehead and potential scapegoat.

Within Hinamizawa, Irie balances dual roles: respected physician and enthusiastic coach of the Hinamizawa Fighters baseball team. His outwardly cheerful and dedicated persona masks an obsession with maid costumes and inappropriate remarks about desiring to marry young patients like Satoko Hojo when older. Despite this, he displays genuine concern for the children's welfare.

His involvement in syndrome research is deeply personal. Diagnosing Satoko Hojo with terminal-stage Hinamizawa Syndrome, Irie initially planned her dissection for research. However, moved by Rika Furude's pleas, he developed an experimental treatment instead, successfully managing her symptoms with regular injections. Similarly, when Satoko's brother Satoshi reached terminal stages in 1982 after murdering their abusive aunt, Irie placed him in a pharmacological coma within the clinic's hidden basement facility. He concealed Satoshi's condition for years while researching a permanent cure.

Largely unaware of Takano's true agenda to trigger the "Great Hinamizawa Disaster," Irie typically committed suicide via sleeping pill overdose in numerous timelines upon realizing the catastrophe's inevitability or facing government retaliation. Only in the final timeline (Matsuribayashi-hen), after Rika revealed Takano's plans, did he actively oppose her and collaborate to prevent the disaster.

Originally conceptualized by series creator Ryukishi07 as a ruthless antagonist who would reveal Satoshi's preserved brain to Satoko, this direction changed after criticism from collaborator BT, shifting the primary antagonist role to Takano. Elements of this darker concept later appeared in the prototype-based "Hinamizawa Bus Stop," featuring an Irie analogue named Dr. Hiroaki Nitta.