Upon the creation of marble launching machines known as B-Daman, people started to participate in the competitive sport B-DaBattles. However, B-Daman contain hidden powers which enhance marble shooting that can be misused for combative purposes.

One night, a certain object residing behind the walls of a restaurant calls upon Yamato Daiwa—a boy raised by cats. Yamato has been having visions of the object which resembles a machine familiar to everyone. Little does he know, hidden behind the walls is not a mere machine, but the fate of the world.