Sumireko is a teenage girl and founder (as well as the only member) of the Secret Sealing Club, a club that seeks to research the occult. After getting word of Gensokyo's existence, she tried to infiltrate the fantasy world, resulting in the events of Urban Legend in Limbo. Somewhere in her occult research, Sumireko learned to use psychic powers, and makes use of it for most of her attacks.