Akane Asahina

Akane is the class representative of Kouta's class. Due to this, she has a high sense of regulations, and therefore disagrees with Kouta's and Chizuru's close high school relationship. She is on good terms with Kouta, and worries about his relationship with Chizuru. She warns Kouta to watch out for Chizuru, though she might be jealous of Chizuru's body.

Source: Wikipedia