While attending Keio University he studied Edo period Japanese literature and the works of European authors.

His literary career began as a student, when he contributed short stories to the journal of Keio University's literature department, Mita Bungaku.

Along with Kikuchi Kan, he was one of the pallbearers at the funeral of Akutagawa Ryunosuke in 1927[2] In 1938, Kojima joined the Pen butai (lit.

[3][4] After World War II he wrote a number of biographical works, including Taifu no Me no yo no ("Like the Eye of a Typhoon"), (later retitled, Suzuki Miekichi), Ogai, Kafu, Mantaro, about the three writers he respected, and Encho.

[citation needed] Kojima lived briefly in Kamakura, Kanagawa prefecture in the 1930s but returned to Tokyo shortly afterwards.