Nanao Nishizuru

The little sister of Nishizuru Yatsuki, she is a ghost unable to re-enter her physical body. Despite now being a ghost she is still seen as happy and playful but it's stated in the manga that she becomes somewhat sad and depressed thinking about her inability to interact with other people (besides Youkai) or objects. After her brother was able to channel Reishi into his hand (Chapter 18) Nanao was able to touch her brother again and as of Chapter 57 her Yatsuki has found a solution to give Nanao back her human body.