Ai Sunakawa

Makoto's older sister. A first-year student at Sakurasaki University in Nagoya. Takeo calls her "Sister." She is a reliable and caring person. She has had a crush on Takeo since she was in sixth grade, but she assumed he would never get a girlfriend because she thought no other girl could appreciate Takeo's good qualities like she did. However, she was heartbroken when Takeo started dating Rinko. Initially, she did not want to accept their relationship, but she empathized with Rinko's troubles about Takeo and supported them, becoming a good supporter of the couple. However, she has not completely given up on Takeo.

She is susceptible to hypnosis and accidentally expresses her lingering feelings for Takeo when hypnotized for fun at a drinking party. This leads Oda to encourage her to confess her feelings to Takeo, but she decides never to convey her feelings and gives up on confessing. Initially, she was almost brought to tears imagining Takeo and Rinko kissing, but gradually she starts to develop feelings for Oda.