Minato Sahashi, a typical ronin student, finds his life suddenly changed after meeting a strange girl named Musubi after finding out that he failed in the university entrance exams in Tokyo. Minato discovers that she is a "Sekirei" and that he is her "Ashikabi" (ie. Master). However, Minato gets into trouble with the landlord when the student is informed that he violated the rules of staying in his apartment.