Mizuki Ashiya is your seemingly cheerful, scrappy young girl living in the United States. However, after becoming enamored with a boy named Izumi Sano who she sees on TV – an up-and-coming pro high-jump athlete – she decides to move to Japan and attend the same all-boys high school, disguising herself as a boy too in order to enroll. Shockingly, however, Sano tells her he has quit the sport and never intends to compete again.