In a drunken stupor, an eccentric, god-like entity called the King of All Cosmos destroys all the stars, Earth's Moon and other such celestial bodies in the universe, save for Earth itself. Despite acknowledging his mistake, the King charges his 5-centimeter-tall son, the Prince, to go to Earth with a "katamari"—a magical ball that allows anything smaller than it to stick to it and make it grow—and collect enough material for him to recreate the stars and the Moon. The Prince is successful, and the universe is returned to normal. A side-story follows the Hoshino family as the Prince works at his tasks. The father, an astronaut, is unable to go to the moon after it is wiped out by the King, and the daughter, whose name is Michiru, "senses" the Prince's work—she can feel when each constellation returns to the sky. Ultimately, the family, along with their house and town, are rolled up in the katamari that is used to remake the moon.