The heroine, Ririka Moriya, is a bubbly (but slightly clumsy) 4th grader who has a crush on Nozomu Kanō, a transfer student from England. On her 10th birthday, Kanō (whom Ririka always calls Kanō-senpai) gives her a magical cap, which allows Ririka to transform into the heavenly guardian, Nurse Angel. Kanō-senpai tells her that he is really named Kanon, and he comes from the planet Queen Earth, which has been overrun by the evil organization Dark Joker. Dark Joker has poisoned that world, and so he was sent to find the legendary Nurse Angel, who would save both Earth and Queen Earth from destruction by finding Flower of Life (命の花 Inochi no Hana). With help from Kanō-senpai and her friend and neighbor Seiya Uzaki, she soon learns to fight as Nurse Angel to protect her friends.