Ayu is the main female character of the story. She is lively and energetic, and wears a backpack with wings on it. Her catchphrase is "uguu", which she uses to express emotions such as frustration, anger, or fear, Yuichi enjoys teasing her about it. She refers to herself as "boku", a Japanese masculine word for "I". Her favorite food is taiyaki. Although she looks very young, she is actually the same age as Yuichi (17 years old).