Kuraudo Ooishi, a veteran detective at the Okinomiya Police Department, was born on November 15, 1923. His biological father perished in a Nagoya air raid during World War II. Post-war, Ooishi reluctantly enforced black market regulations as a policeman. During this duty, he met an older man resembling his father who became a significant father figure; this man later managed the Hinamizawa Dam construction. The dam manager's brutal lynching and dismemberment by his own employees during the 1979 Watanagashi Festival became pivotal for Ooishi. He blamed the anti-dam movement led by the influential Sonozaki family, fueling his determination to expose them as responsible for Hinamizawa's subsequent mysterious deaths. His aging mother and impending retirement added urgency to his investigation. Ooishi blends amiability with intimidation in his investigations. He initially presents himself as lighthearted and reliable, particularly to outsiders like Keiichi Maebara, leveraging their newcomer status to extract information about village secrets. His methods involve psychological manipulation and withholding critical details, inadvertently heightening the paranoia of those he questions. His persistent accusations against the Sonozaki family strain relations with villagers, especially Mion Sonozaki. This mutual distrust earns him the moniker "Oyashiro-sama's messenger" due to the coincidental deaths or disappearances of individuals he contacts shortly afterward. In darker arcs, his tactics escalate to physical aggression, including forcibly restraining Keiichi or coercing him during a corpse excavation. Despite bending police protocols, his core motive remains solving the cases before retirement, driven by duty and personal vengeance for his surrogate father. His role evolves across multiple timelines. Early arcs show him interviewing Keiichi after Tomitake's death, revealing background on Rena's institutionalization and the histories of Satoko and Rika's families, intensifying Keiichi's suspicions. In Watanagashi-hen, he strategically leaks information about Shion's disappearance to Keiichi, intending to use Keiichi's potential disappearance as a pretext to raid the Sonozaki estate. Tatarigoroshi-hen features his most confrontational portrayal, physically assaulting Keiichi and overseeing a fruitless search for Teppei Houjou's body. Conversely, Himatsubushi-hen depicts his competent 1978 collaboration with detective Mamoru Akasaka to rescue the Minister of Construction's kidnapped grandson. Years later, after Rika's death and the Great Hinamizawa Disaster, he and Akasaka co-author "Higurashi no Naku Koro ni" to preserve the truth. In later storylines, learning the Sonozakis were not responsible for the dam manager's death leads to reconciliation, even forming a mahjong group with Akane Sonozaki. Physically, Ooishi is a muscular yet overweight man in his late fifties, with short grey hair, green eyes, and a habitual cigarette smoker favoring Gaster brand. He typically wears a cream suit, black shirt, red tie, and suspenders, often carrying his jacket. Despite his unassuming appearance, he possesses unexpected physical prowess, skilled in wrestling and hand-to-hand combat, contributing to his intimidating reputation. Outside police work, he enjoys mahjong and aspires to become a professional ballroom dance instructor. The phonetic similarity of his name to "oishii" (delicious) earned him the fan nickname "Detective Delicious". Post-retirement, Ooishi relocates with his elderly mother to Hokkaido, fulfilling a long-standing promise. He continues investigating the Great Hinamizawa Disaster alongside Akasaka, ensuring the events are documented in their book. His legacy is one of relentless truth-seeking, employing ethically questionable methods but ultimately aimed at achieving justice for the victims of Hinamizawa's tragedies.