Higuchi Kotarou is a slightly cool sixth grader preparing for junior high school entrance exams. His mother died in an accident when he was young, and now he lives an ordinary but peaceful life with his busy father. One day, a mysterious girl named Misha moves into the room next door to Kotarou's house. When Misha finds out that Kotarou does not have a mother, she declares that she will be Kotarou's mother and wants to take care of him in any way she can. In fact, Misha is actually a half-human angel who came to the human world to stand on her own...