Yuma Tsukumo, an amateur duelist determined to become Duel Champion despite his reckless style, challenges Ryouga, the biggest troublemaker at his school, to a match. The duel unexpectedly awakens Astral, a memoryless spirit whose past has been scattered across the world as mysterious "Number" cards. Bound to help each other, Yuma and Astral start hunting down the Numbers one duel at a time, using Xyz Summoning, a new method that stacks monsters of the same level, to turn ordinary card games into a search for Astral's lost identity.