We Love Katamari tells two stories: a self-referential story of how the King of All Cosmos is reacting to the unexpected success of Katamari Damacy, and an origin story of how the King of All Cosmos became the King of All Cosmos, met his wife, and had his son.
Reaction to the success of Katamari Damacy:
After completing his goal to recreate the stars in the sky, the King of All Cosmos was surprised to discover that he had many fans down on Earth. Thus begins We Love Katamari, where the King of All Cosmos seeks to help fulfill the wishes of his fans—with the help from his son and his son's cousins, who again travel Earth, rolling things up into a Katamari.
The King of All Cosmos’s origin:
The King of All Cosmos's history is told in We Love Katamari’s cut scenes, interspersed between the game’s stages.
The King of All Cosmos was not always the King. His father was the previous King of All Cosmos (also called Emperor of the Cosmos, or Papa). The future King of All Cosmos grew up either on Earth itself or a planet very much like it, in a giant castle on a hill surrounded by green fields. (Though, early in the game, we are to believe all action takes place in a world called “The Great Cosmos”.)
