Dragon Ball Z Movie 12: Fukkatsu no Fusion!! Gokuu to Vegeta

A careless accident in the Other World lets a mountain of corrupted energy engulf a young worker, transforming him into Janemba. The bizarre demon distorts the afterlife, breaks the boundary separating the dead from the living, and traps King Yemma behind a warped barrier. Goku, already dead and competing in the Other World, rushes to confront the source of the chaos.

Janemba's childish form proves dangerous enough, but his next transformation overwhelms even Goku's greatest power. With the universe itself twisting around them and the dead spilling back onto Earth, Goku is forced to rely on the one warrior he least expects to cooperate with: Vegeta. Their only chance may require the two rivals to become something neither can achieve alone.