Kotaro Satomi (voiced by Yuichi Nakamura) is a seemingly ordinary high school student who lives in Room 106 of the Corona House, where the rent is extremely cheap, and leads a quiet life. What Kotaro never expected was that one day, his uneventful life would be completely changed by the appearance of a girl. The girl's name is Sanae Azuma (voiced by Eri Suzuki), and her true identity is actually a ghost living in Room 106. After the plan to scare Kotaro away failed, Sanae gradually got used to the life of "living together" with Kotaro. Sanae is not the only one who wants to compete with Kotaro for the room. The hot descendant of the ancient civilization Kurano Kirika (voiced by Mosumi Tazawa), the unexpected magical girl Nijigan Yurika (voiced by Higashi Omori), and the princess Tia Mislin (voiced by Maria Naganawa) who came from outer space. These beautiful girls who appeared one after another, each of them took Room 106 as the target of invasion. In order to protect the cheap rental house on which he depends for survival, Kotaro's "war" begins.