In this world, trophies fight. They know nothing but fighting. Fighting is the sole reason for their existence. Being turned back into a trophy, being unable to fight, is much like death. Those are the rules of this world. But...When someone...or something...breaks those rules, the world will pay a terrible fate

The story begins with Tabuu, the "embodiment of Subspace". Tabuu resides within Subspace, a realm of empty darkness, and wishes to destroy the World of Trophies by breaking it to pieces