Koakuma is a minor character in the Touhou Project series, appearing as an assistant librarian in the Scarlet Devil Mansion’s library, Voile. Her name, which literally means 'little devil' in Japanese, reflects her demon-like appearance and mysterious background. Koakuma works under Patchouli Knowledge and assists with organizing magical tomes. Despite her limited appearances and unnamed status in the games, she has become a popular character in fan works, often depicted as diligent and friendly, supporting the main cast.