Mizuki Ashiya, who is Japanese, but moved to America when she was young, is the heroine of the story. She spontaneously moved from California to Japan and enrolled into an all boys school (Osaka Gakuen) because her idol, Sano Izumi, who’s a top high jumper and the same age as her, attends the school. To look like a boy, she keeps her hair short and ruffled and wears a tight demin vest to hide her boobs. In many ways, it’s good that she has a pretty flat chest, but she wants more cleavage. She’s a very fast runner (due to her mother’s athleticism), but is very clumsy at times (due to her father’s clumsiness). Mizuki loves all kinds of food, especially sweet things, which is a strong contrast to Izumi's dislike of them. Also, she can be quite stingy when it comes to sharing her food. She’s also a lover of animals, as we can see when she’s with Yujirou, Sano’s dog.