Yuyuko Saigyouji is a ghost girl who dwells in Hakugyokurou. She serves the important duty of managing the phantoms in the Netherworld. She appears to have a somewhat carefree personality, but she can be unexpectedly wise and bold at times. Youmu Konpaku is her fencing instructor, bodyguard, and gardener.

Hakugyokurou is where Yuyuko Saigyouji "lives" together with Youmu Konpaku and the phantoms. Its gardens are extraordinarily vast, so taking care of them must be quite a tough job for the gardener. When Yuyuko wants to perform a dance, she probably does it in these gardens. Incidentally, "becoming a member of Hakugyokurou" is a euphemism for dying.

Ghosts are a type of spiritual entity that has somehow retained the form of a deceased human. It's said that when humans die with vengeance in their hearts, they become ghosts instead of phantoms, but this doesn't seem to be the case for Yuyuko.

People live, and they die. For living creatures, the concept of death always exists as a fantasy since no one can experience what death is truly like while they still live.

"Youmu, let's sleep in the same futon tonight." "Huh?! I'm no longer a child." "Oh, I thought you were the little Youmu again." "You say the strangest things!" "Or maybe I thought I turned back into a child." "What are you talking about?" "So, is that a yes?" "Hmm, all right, fine. I'll sleep beside you." "Teehee, thank you, Youmu."