Rikuo's former classmate and close friend. She taught at the same high school Haru attended. She only wishes to be friends with Rikuo. She feels at fault for Haru dropping out.
SpoilerShe loved Rou's brother a long while ago, but when he passed away, she found it hard to love again. She loved him because of how hard he tried to be unpleasant, knowing he was going to die young, he didn't want others to be attached to him. She has known Rou and his family for a long time now. She tries to avoid the topic entirely and does not talk to anyone about it.
(Source: Yesterday wo Utatte Wiki)