When Koutarou's father relocates for work, Koutarou seeks an affordable living arrangement during high school and settles on Room 106 at Corona House. Surprised by the unbelievably low rent of 5,000 yen a month and charmed by the lovely landlady, he believes he's struck gold. However, his bliss is short-lived as unexpected guests start showing up, including a ghost named Sanae, a magical girl named Yurika, an underground dweller named Kiriha, and an extraterrestrial princess named Theiamillis. All of them assert their need for the apartment, demanding Koutarou's immediate departure. Unwilling to surrender his newfound haven, Koutarou decides to stand his ground. To prevent chaos, the landlady intervenes and mandates a peaceful resolution to determine the apartment's rightful occupant. Will Koutarou lose his home before even unpacking, or will he successfully evict his unwelcome visitors?