Youmu is the gardener of the netherworld pagoda, Hakugyokuro. She comes from a very rare breed, the half-phantoms; in this strange combination, the human half and phantom half exist in physically separate bodies, but are always close by one another. Youmu is very young for a half-phantom, under 60 years; her exact age is unknown. While straightforward, focused and loyal to her mistress, Yuyuko, Youmu is still rather immature, and tends to be a target for teasing by the other girls of Gensokyo. Paradoxically, she is afraid of ghosts. Her talents are swordfighting and speed. In the games, she is characterized by creating powerful danmaku with her sword slashes, and slowing time.