Adolescence who was ignorant of fantasies, high school student Yuki Rito fell in love with Banhua Haruna, emboldened herself time and time again, and confessed to Haruna the next day . When Ridou was taking a bath at home at night, an explosion occurred in the bathroom, and the beautiful girl Lala fell from the sky. According to Lala herself, she was a princess who fled from the planet Debiluk, and she was forced to live in Ridou's house like this. Lala's graceful figure made Ridou unable to help herself, and Ridou actually reached out to Lala's chest. According to the regulations of the planet Debiluk, touching the breast is equivalent to entering into a marriage contract. Rito thought it was too hasty, and wanted to break off the engagement, but the condition was that he would touch the girl's breasts again within the agreed time. Rito was in a tangle. The king of Planet Debiluk went to Earth to test his daughter's fiancé, to find out if he could become his heir, and asked to arrive at the king's place within 24 hours. Rito rushed desperately, but on the way, he received a call from Haruna requesting to meet. ..