Happy Lesson (2001)

Original title: HAPPY☆LESSON

15-year-old Chitose Hitotose moves out of the orphanage back to his vacant parents' house and finds himself very alone and unhappy. But when five of his female high school teachers decide to move in with him to become his new mothers, he learns that the chaos of their constant attention and concern change his life for the better, if only to teach him about the very special meaning of being part of a family and enjoying a quiet moment.