Yuyuko is the ghost 'princess' of Hakugyokurou, the netherworld of the "formerly-living", but was once a living human. Long ago, after her death from suicide, her body was used to place a seal on the Saigyou Ayakashi, a dangerous youkai cherry tree, to stop it from killing innocent humans.
Humans fear Yuyuko because of her fearsome power and a general fear of the supernatural, but she is very cheerful and friendly. Unlike many ghosts she resembles a living human, and her playful, good-humored personality, otherworldly beauty, and courtesan charm can have a disarming effect. She seems to never take anything too seriously though and she loves to tease her straight-laced and eager-to-please assistant, Youmu, who is her opposite in many ways. She is also known for her incredible appetite and seems to have a food-related metaphor for any situation. Yuyuko is truly "dead and loving it."