A Black Hole as a highly dense star with an immense gravitational pull. At the beginning of Beautiful Katamari, the King of All Cosmos gets a little overzealous with a tennis serve, accidently warping space and creating a black hole. It sucked in all the stars and planets that the Prince had made during Katamari Damacy and We ♥ Katamari. Seeing the problem, the King sends the Prince to make more stars before people notice, culminating in an attempt to plug the black hole and save the new stars from also being destroyed.
The Black Hole can be plugged or rolled up in the Make Uranus stage or the Make a Supergiant stage. It must be at least 420k kilometers to roll up the hole. There is also a present inside it.