The young cousin of the Protagonist and Ryotaro's only daughter. Nanako is a very innocent character, but is usually left at home due to her father's work.

Nanako is capable of taking care of herself and watches TV most of the time. She treats the Protagonist as an older brother and tries to do whatever she can to spend time with the family members.

Nanako mostly talks about the afterlife and asks where good and bad people go. The Protagonist helps Nanako come to terms with her father's busy professional life, realizing that he also missed her mother as much as she did.