Waku Waku☆Wakusei Princess

While driving in the mountains, the hero crashes his car. As he pleasures himself under the stars, one star plummets to Earth. Rushing to the crash site, he discovers it's a spaceship. Out steps Princess Pam, an alien girl, who claims that the energy from his masturbation caused her ship to crash. She declares him responsible and orders him to help collect energy—which can only be generated through sex with girls. To gather enough, it must be done multiple times.