As a child, Oshimi was drawn to modernist poetry from authors such as Sakutaro Hagiwara and Mitsuharu Kaneko. He also admired surrealist artists like André Breton, Max Ernst, and Paul Delvaux. His favorite artist is Odilon Redon, while Francisco Goya also holds a special place in his heart. In his youth, Oshimi strongly identified with the protagonist of Tetsu Adachi's Sakura no Uta, which later influenced his manga Aku no Hana. In 2001, he was awarded the Tetsuya Chiba Prize.