Kuraudo Ōishi serves as a veteran detective at Okinomiya Police Station, relentlessly investigating the annual deaths and disappearances tied to Hinamizawa's Watanagashi Festival. His personal stake began when a dam project manager—who acted as a father figure after Ōishi's biological father perished in a WWII Nagoya bombing—was lynched and dismembered by workers. This incident, dubbed the first victim of "Oyashiro-sama's Curse," cemented Ōishi's conviction that the Sonozaki family orchestrated the tragedies to oppose the dam. He dedicates his career to exposing them. Approaching retirement around age 59 in 1983, Ōishi escalates his efforts. He targets outsiders like Keiichi Maebara, exploiting their unfamiliarity with the village to extract information. His tactics involve psychological manipulation, such as fueling Keiichi's paranoia with theories about the Sonozaki family or Rena's institutionalization. Though initially affable, he reveals ruthlessness through physical intimidation—forcibly kneeling Keiichi for noncompliance—and implying readiness to sacrifice informants who "disappear" during probes. Villagers distrust Ōishi, nicknaming him "Oyashiro-sama's Messenger" because those he contacts often vanish or die. Ironically, while he suspects village-wide collusion, locals view him as a potential perpetrator. Post-retirement, he plans to relocate to Hokkaido or Sapporo with his elderly mother but continues investigating. With former colleague Mamoru Akasaka, he authors *Higurashi no Naku Koro ni*, documenting the "Great Hinamizawa Disaster" to ensure the mysteries endure. Muscular yet portly, Ōishi has gray hair and green eyes. He typically wears a cream suit jacket over a black shirt, red tie, and suspenders, rarely without a Gaster-brand cigarette. Skilled at mahjong, he aspires to teach professional ballroom dancing. Despite his demeanor, he excels in hand-to-hand combat and wrestling, honed through police work. Ōishi embodies ambiguity: his trauma-driven quest for justice veers into obsession, violating ethics yet seeking closure. Relationships reflect this complexity—adversarial with Mion Sonozaki over accusations against her family, cautiously cooperative with allies like Dr. Irie, and mentorship-oriented with junior officer Katsuya Kumagai. In *Matsuribayashi-hen*, he reconciles with Akane Sonozaki, joining her mahjong games for uneasy camaraderie. During *Tataridamashi-hen*, Hinamizawa Syndrome exacerbates his instability; he murders villagers including Shion, Mion, and Satoko, showcasing his duality as both investigator and perpetrator.