Other source:
Gohan fully powers up, and just as Shin predicted, Spopovich and Yamu suddenly attack him. They stick a weird device inside him, steal all of his energy, and then leave. Shin takes off after them, and Goku, Piccolo, Krillin, and Vegeta follow. Kibito heals Gohan, and those two and Videl also leave. Shin explains that long ago there was a wizard named Bibidi who created a monster with unbelieveable destructive power. Shin killed Bibidi, and the monster, Majin Buu, was left sealed in a ball. Now Bibidi's son, Babidi, has come to resurrect the monster, and they plan to use Gohan's stolen energy to do it.
