Ajimu Yasuna, the eponymous character, lived in Tokyo until a few months before the beginning of this story but now attends the same high school as Suzue. She likes music, history and the Japanese language, all of which results in her composing and playing her own songs: As a side job she plays Hawaiian music on her ukulele twice a week in the bar J.O.D..
When she meets Hirosuke the first time she mistakes him for a molester first, then considers him a stalker when the boy desperately tries to clear up the misunderstanding, before they eventually form a friendship. But Yasuna hasn't moved on after learning about the death of her former boyfriend Otomine Yuuma.