Hatsukoi Monster

Fifteen-year-old Kaho Nikaidou moves to a Tokyo high school dormitory after leaving her protected home environment. While adjusting to her new life, she nearly gets struck by a truck but is rescued by an attractive man. She becomes infatuated with him and, after locating him, confesses her feelings. It is revealed that the man who saved her, Kanade, is the son of her new landlord. He accepts her invitation to go out with her, but Kaho soon discovers a surprising truth—her new boyfriend is only in the fifth grade.