Shinichi Ōhara is the eldest son of the Ōhara family and older brother to Shota Ōhara. He attends junior high school, while Shota is in elementary school. Shinichi maintains an average academic record, contrasting with Shota's poor grades and position near the bottom of his class. At home, Shinichi frequently listens to music, favoring records by the Beatles and Elvis Presley. Romantically, he tends to confess his feelings to girls he finds attractive, though these confessions are described as easily swayed or superficial.

Within the Ōhara household, Shinichi interacts with the resident ghost, Q-Taro, and other characters including Tsuyoshi Saigo (nicknamed Godzilla), Kizao Kiza, Yoshiko Koizumi, Hakase, and Doronpa. In the 1985 anime adaptation, he gains a girlfriend named Yukari Kawai, a fellow middle school student. P-ko, Q-Taro's younger sister, resides with Yukari, further connecting Shinichi to the supernatural characters. Shinichi's name derives from Shinichi Suzuki. His role centers on his position as the older brother and his everyday interactions within the household dynamics alongside both human and supernatural companions.