Koutarou, a high school student, must find a new place to live after his father's work transfer. He discovers a surprisingly affordable apartment, Room 106 at Corona House, with a beautiful landlady. However, his peaceful living arrangement is disrupted by a series of unexpected visitors, including a ghost, a magical girl, an underground dweller, and a princess from outer space. Each claims they need the apartment for their own reasons and demands Koutarou vacate immediately. But he refuses to give up his cheap home without a fight.
With the help of his friend Kenji Matsudaira, Kōtarō Satomi moves in to room ...