Rito Yuki, a high school student, struggles to confess his feelings for Haruna Sairenji, who is not available due to circumstances beyond their control. One day, while sulking in the bathtub, he encounters an unknown female figure. Her name is Lala, and she comes from the planet Deviluke as the heir to her father's throne. Her father has arranged a marriage with one of the husband candidates on the planet but decides that Lala should marry Rito instead due to his love for him. Commander Zastin orders to bring Lala back home and battles Rito already, informing Emperor that they can only marry if it is with someone you love. Despite initial reluctance, Lala falls in love with Rito after hearing him defend her honor. Her father agrees to allow their marriage as long as Rito can protect her from other potential suitors. However, if he fails to meet his expectations and cannot protect her, Lala's father plans to kill Rito and destroy the Earth.
A socially awkward boy navigates the challenges of adolescence, struggling to...