Later Gohan decides to go to college and everyone believes that times of peace are among them. Several years later Goku says he is going to the next Martial Arts tournament and everyone else meets there. It is discover that Gohan has a girlfriend from college named Videl. They all participate in the tournament and meet up with Supreme Kai and Kibito. It is discovered that Babididi is trying to free Majin Buu using the energy at the tournament the Z fighters confronts Babididi and he turns Vegeta into a Majin. Vegeta challenges Goku and he powered up to Super Saiyan 3 and Goku shows that he can also go Super Saiyan 3.After they fight for a while Majin Buu is released from his prison. Vegeta knocks Goku out to challenge Buu. Vegeta sacrificed himself to save the world only to be in vain as Buu then regenerates. Goku is returned to the underworld because of the strain of his Super Saiyan 3 shortened his day on earth. Gohan then fights Buu in Super Saiyan 2 but can't win. As is nearly killed by and energy beam Supreme Kai saves him and teleports him to the Planet of the Kai's. Goku senses Gohan energy and teleports to him to discover Gohan training with the Z sword. The Z sword is broken and Elder Kai is freed from him. The notice that Buu is causing mass destruction and Goku suggest the fusion dance then Elder Kai Suggest potara fusion he gives Goku his life force then hands Goku and Gohan his earrings and tells them they will be permanently fuse. Gokan is born.
Gokan teleports to Buu's energy and discovered that he has changed his from and becomes stronger Gokan fights him then senses Vegeta's energy. Gokan tells Vegeta to distract Buu while he goes and seeks advice from Elder Kai. Elder Kai decides to unlock Gokan's energy.
Ultimate Gokan teleports back to earth as Vegeta is wearing down. Vegeta Returns to the otherworld as his energy is used up and can no longer be on Earth. Gokan and Buu are in a beam struggle. Gokan removes one of his hands to charge up another beam, then Gokan teleports behind Buu and kills Buu with the second beam. The Earth is safe once again.
The Dragon Balls are collected and the Z fighters summon Shenron, The first wish is for everyone killed by Buu other than Babididi to have their lives restored, and the Second wish is for the fusion of Gokan to be reversed.