Koizumi Yakumo is the Japanese name adopted by the writer and Japanologist Patrick Lafcadio Hearn after becoming a naturalized citizen of Japan in the late nineteenth century. Born in Greece in 1850 to a Greek mother and an Irish father, Hearn spent his early life in Ireland and the United States before settling in Japan in 1890. Rather than functioning as an original creator of manga or anime, Koizumi is recognized as a foundational source of source material for such works, primarily through his extensive collections of Japanese folklore, legends, and ghost stories.

His most influential work in this context is the 1904 collection Kwaidan: Stories and Studies of Strange Things, which includes well-known tales such as “Yuki-onna” (The Woman of the Snow) and “Mimi-nashi Hoichi” (Hoichi the Earless). This collection has been adapted into various visual media. The most notable adaptation is the 1965 film Kwaidan, directed by Masaki Kobayashi, which presents four of Koizumi’s stories as a cinematic anthology. The Criterion Collection release of this film explicitly notes that it is based on the writings of folklorist Lafcadio Hearn, also known as Yakumo Koizumi.

As a writer, Koizumi did not create manga or storyboards for anime series. Instead, his artistic identity is that of a chronicler and popularizer of Japanese cultural traditions for a Western audience during the Meiji era, as well as a preserver of these stories for a Japanese audience. His significance to the anime and manga industry lies in his role as a primary source. His books, such as Kwaidan, Kottō: Being Japanese Curios, and In Ghostly Japan, serve as a repository of classic ghost tales, yokai legends, and historical narratives that later manga artists, anime screenwriters, and film directors have continuously adapted and reimagined. His name appears in credits not as a direct creator, but as the original author of the folklore or literary works upon which modern adaptations are based.