Mayu Miyano is the childhood friend of Takashi who lives directly across the street from their house. She is depicted as a busty meganekko who is ditsy, clumsy, and has a timid personality. Mayu secretly has feelings for Takashi but doesn't have the courage to confess to him. Because of this and her close history with Takashi, she is perceived by Yamada as a rival for his virginity. One of her favorite hobbies is cooking. Her first love was actually Takashi's sister Kazuki, who she thought was a boy.

Miyano's erogami is dressed as a fairy princess and gives innocent advice such as kissing the cookies she gives to Takashi is like giving him an indirect kiss.