A few years have passed since Goku first met Uub, he's become satisfied that Uub is becoming stronger while he trains him so decides to take him to the next Tenkaichi Budokai tournament in order to test him.

In the background, a mysterious adversary from a different universe, Universe 0 (This was long before Dragon Ball Super) wants to return to our universe. In order to achieve that task, he requires the power of the Dragon Balls, and has revived Babidi in order to accomplish that goal.

Babidi soon awakens the remnants of Majin Buu sleeping deep within Uub and turns him into his puppet. Now it's up to Goku and Co. to stop this new adversary from crossing over into their universe at all costs!