Nana Nishino (西野 菜々, Nishino Nana) is Aoki's ex-girlfriend whom she dated during his 1st year in junior high before moving to Sendai due to her family's work-related issues. As a child, Nana lived near Aoki and the two were very close, their friendship eventually blossoming into a brief romance.
Nana has dirty-blonde hair and dark-brown eyes. She is said to bear a striking resemblance to Yui Kiriyama and fashions her hair with a hair-clip. Nana states to have cut her hair to neck-length after moving away.
- Aoki Yoshifumi: Aoki states that even though they were young and immature, what he felt for Nana was definitely love, and as a result, she is very special to him. During the events of the Kako Random arc, Aoki decides to meet with Nana despite having been separated for so long and is able to put their past behind him. Though their reunion was brief, both were shown to be very pleasant towards each other, like old friends.
- Excluding his family and his time spent reverted to a child, Nana is the only person to refer to Aoki by his given name, "Yoshifumi," in the entire series.
- In the light novel, it is only mentioned that Nana lives in the north in Prefecture M; however, in the anime, there is a sign that confirms she lives in Sendai.