Gedoumaru is a Shikigami of the Ketsuno Clan. She was given to Sakata Gintoki of the Yorozuya as a precaution, during the Exorcist Chapter, by Ketsuno Ana, who had requested the Yorozuya's assistance.

Cold and relentless, Gedoumaru will do anything to beat her opponent, as seen in Episode 195 when she tricked the other Shikigami into thinking her mother had just died, when it was all just an act to get them to lower their guard. If her master shows any sign of weaknesses, she will turn on him.

Gedoumaru was caught by the Ketsuno clan when she was tearing up Mt. Oe during the Heian period, and was forced to serve them ever since, as told by Gedoumaru herself in Episode 195.