Janemba is the main antagonist of movie #12, Dragon Ball Z: Fusion Reborn. He is a demon of pure evil and great power created when a teenage ogre, also known as the Saike Demon,[1] who was responsible for watching the spirit cleanser in Hell, slacked off, and the cleanser exploded as a result of the ogre's carelessness. The evil formed around him to create a giant, yellow, and childlike being that turns Hell into his own paradise. Goku and Pikkon are interrupted from their match in the Other World Tournament to fight Janemba, Pikkon being left behind to free King Yemma from the barrier that Janemba created around his castle. Eventually, Janemba's weaker first form is destroyed by Goku, forcing a transformation to his second state, which enables him to overcome Goku. Vegeta appears and assists Goku, but both of them are not strong enough to defeat Janemba. The two eventually defeat Janemba by fusing into Gogeta, who destroys Janemba by purifying his pure evil energy and turning him back into the Saike Demon.

Janemba in the Dragonball Wiki! <-- KLICK!