Kid buu was sent to hell by mistake. So while in hell kid buu found Janemba and fought him. During the fight Kid buu adsorbed Janemba and escaped from hell for revenge. He killed Goten, Gohan, Kid Trunks, Piccole, and Hercule. So Goku and Vegeta fused into Gogeta level 4. So Buu and Gogeta fought and Buu was defeated by a near death from Gogeta, with there special move Final Kamehameha times 100. Finally, Goku and Vegeta revived them with the dragon balls. But Buu swore that one day he will come back again stronger.
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