Nurse Angel Ririka SOS is the story of a 10 year old 4th grade girl named Moriya Ririka. She is, like most Magical Girls, bright, cheerful, extremely cute, and a bit of a clutz. She has blonde hair that she wears in a ponytail, and brown eyes. Ririka’s best friend is a boy named Seiya, who is the son of a doctor and her next-door neighbor. Seiya stands by Ririka’s side throughout the series, both in times when he is powerless to help, and also when he is stronger than you’d expect.
In Ririka’s case, there is no personal talking pet companion to give her the magical items, or to act as an advisor. Instead, it is the handsome and mysterious new boy in school, Kanou-sempai, who gives Ririka her “birthday present”, a pink and white nurse’s hat. The hat gives Ririka the power to turn into the beautiful Nurse Angel, a heroic girl warrior clad in a pink and white nurse’s uniform. As the Nurse Angel, Ririka seems a bit older than her normal self, and her hair grows longer, escaping her ponytail.
The villain or evil world Ririka must fight against is called the ‘Dark Joker’. It seems that the evil Dark Joker has already wasted Kanou-sempai’s home world of Queen Earth. Kanou’s real name is Kanon, and he is a messenger from Queen Earth, sent to find the legendary Nurse Angel who has the power to fight Dark Joker and save both their worlds. Ririka’s main quest, aside from fighting various monsters, is to find something called the Flower of Life that will yield the Green Vaccine that will stop Dark Joker for good and heal the universe.