In the summer of 2006, brothers Hibito and Mutta Nanba spot a strange UFO which flies off to the moon. In 2025, Hibito has since become an astronaut who is due to go on a mission towards the moon. Mutta, on the other hand, has just been fired from his job at an automobile company for head-butting his supervisor and has to move in with his parents. Upon hearing about Mutta's job loss, Hibito sends him an e-mail telling him to listen to the tape they recorded on that day in 2006...