Touhou Soujinengi: The Genius of Sappheiros is a fan-made Touhou Project game and a traditional turn-based RPG released at Comiket 78, heavily influenced by traditional console roleplaying games such as the SaGa Series. Despite being an RPG, it follows a traditional Touhou stage-based format, with each stage being its own dungeon.

It's a normal day in Gensokyo when Reimu Hakurei notices a strange fog rolling in. All across Gensokyo, residents witness this fog weakening and killing a great many lesser youkai. At the behest of Yukari Yakumo, she joins forces with Marisa Kirisame, Sanae Kochiya, and Aya Shameimaru to investigate the fog's appearance...