Risai is a youkai more specifically a MakuraGaseshi. MakuraGaseshi are said to be able to draw out the soul of someone who is sleeping by switching their pillow around. It is also said they are very mischievous. He is introduced in chapter 57. When he met Nanao he said she should stay in her current form eternally young because she is his type. He used his ability as a youkai in order to help Nanao become human again however she was unsuccessful. He told her she needs more spiritual power. He said he suspected this when he first met her. He later gave a solution to the fact that Nanao lacked spiritual power so the next attempt will be successful.