Yuuki Rito (voiced by Watanabe Akino) is upright, cheerful, careful and friendly. Rito has always been secretly in love with her childhood sweetheart Haruna Nishirenji (voiced by Yahagi Sayuri), but Rito, who knows nothing about love, just buries this strong feeling deep in his heart. Finally, Rito can no longer suppress his love for Haruna, and he repeatedly musters up the courage to confess to Haruna. By chance, a girl named Lala (voiced by Tomatsu Haruka) appears in front of Rito from the sky. In a strange combination of circumstances, Lala becomes the object of Rito's confession. In this way, Rito and Lala, who claims to be an alien princess, begin to live together. It is from this time that the killer Shadow (voiced by Fukuen Misato), Lala's sister Nana (voiced by Ito Kanae) and Mengmeng (voiced by Toyosaki Aiki) and others come to Rito one after another.