During this time, Supreme Kai has been desperately trying to find Gohan when the recently returned to life Kibito finds both and heals them.
Supreme Kai then teleports them all to his own planet. The first mortal to actually step foot on the Sacred World of the Kai, Gohan begins training with the Z Sword after pulling it from the stone. Meanwhile, Goten and Trunks wake up, and Goku tells them about Gohan and Vegeta, which makes them cry about their deaths, but are angry at Goku for not saving them, even though this is actually not Goku's fault.
Goku calms them down by repeating his belief they can face against Majin Buu.
Goku subsequently begins to teach Goten and Trunks how to do the Fusion Dance.
Goku has learned this technique from an alien race called the Metamori, during the seven years after Super Perfect Cell's defeat in the Other World.
They will take a long time to learn this, more time than Goku has. Since Goku is pressed for time, he ends up showing Piccolo the dance so that he can continue the training. Meanwhile, Babidi desperately threatens to return Majin Buu to his ball unless Majin Buu complies with his orders. Babidi is on a mission to find Piccolo, Goten, and Trunks because of their earlier interference.
To help speed this process, Babidi telepathically communicates with the people of Earth, forcing them to watch Majin Buu as he attacks a city.
Majin Buu converts the entire population into jawbreakers which he sucks up in one mighty gasp and eats. He then levels the city much to Babidi's delight.
The next city suffers the same fate, as he turns the population into chocolate bars. Babidi soon learns where Trunks lives and telepathically tells the group that he is on his way to kill the boy.
Bulma alerts Goku that her parents are about to be killed and also mentions that she left her Dragon Radar at her house. Goku asks Trunks to go to West City and get the Dragon Radar before the city is destroyed.
In order to buy time for Trunks to get the Dragon Radar, Goku approaches Majin Buu and Babidi, and starts giving them a show of his strength. He figures this will be enough to impress Babidi, stall him, and keep Majin Buu occupied, also stalling him. Goku transforms into a Super Saiyan, then a Super Saiyan 2, and finally transforms into the long-haired Super Saiyan 3.
The energy unleashed in this form startles everyone across the planet. Even Tien and Chiaotzu feel the power of the Super Saiyan 3.
Babidi does not seem too impressed with the first two forms since he has already witnessed them in Vegeta and Gohan, but the third one has a different effect.
This still does not give Trunks enough time, so Goku decides to battle against Majin Buu. The battle starts off at a quick pace as Goku demonstrates his new powers. Goku once again holds back his efforts, because he knows that it is not his job to save the Earth anymore and he wants to let the new generation, Goten and Trunks, take over for the planet's protection.
Eero was speechless looking at Goku not doing well, 'This guy is really retarded, he is training his younger generation against an oponent which they can't defeat.'
During this battle, Goku is able to obtain the upper hand, but cannot cause any permanent damage to Majin Buu, who regenerates from his every attack and even shocks Goku by performing one of Vegeta's techniques.
After a while, Trunks finds the Dragon Radar after Dr. Briefs tells him it was in one of the capsules and Goku senses him returning to the Lookout. Goku returns to his normal state, admitting he can't defeat Majin Buu and asks Babidi to wait two days without killing people so Trunks and Goten can complete their training and fight Majin Buu. Babidi refuses but Majin Buu is eager, so Goku leaves to return to the Lookout.
Babidi berates Majin Buu for letting Goku escape, but Majin Buu grows tired of Babidi and, through simple trickery, is able to dispose of the wizard by punching his head off and then disintegrating his body. In between bouts of mass destruction and his childish-like acts, the Majin builds a house and meets Mr. Satan.
Eero was assessing and analyzing all the attacks and flights learning, New use of Qi and technique.
'It seems watching these battles are really rewarding. Also why am I feeling that i can defeat this guy easily?' Eero thought to himself,
Trunks returns to the lookout with the Dragon Radar and Piccolo asks Goku why he didn't defeat Majin Buu, Goku tells Piccolo that his Super Saiyan 3 transformation is a short transformation, and it isn't his battle to win.
Eero also appeared on the Lookout, after witnessing cities destruction and Majin Buu walking inside the Satan city.
Piccolo tells Goku that when he returns to the Other World and sees Gohan there, Piccolo asks Goku to tell him that he is proud of him. With the Dragon Radar safe, Goten and Trunks continue practicing fusion, but want to see Goku's Super Saiyan 3 transformation and Goku reluctantly agrees as Goten and Trunks promise to train harder.
However, the Super Saiyan 3 transformation has decreased Goku's time on Earth, so when he arrives at the lookout, it is already too late as Fortuneteller Baba tells Goku that his 24 hours are up.
He must go back to the Other World and allows Piccolo to pick up where he left off as Piccolo agrees and also tells the others that he will find Gohan in the Other World after giving Chi-Chi and Goten one final hug and telling that he will tell Gohan that he said hi when he sees him in Other World after Chi-Chi asks what is she going to do now that Gohan is gone, but Videl thinks that Gohan is still alive and Goku says goodbye to his friends and family before he returns to the Other World.
Piccolo continues to teach the boys the Fusion Dance and, after two mishaps where they fail miserably, they successfully fuse to make the warrior Gotenks. Gotenks then flies off to fight Majin Buu, who still proves to be stronger and subsequently beats him.
In Other World, Goku asks King Yemma to see if Gohan checked in but finds that Gohan is still alive, just like Videl said.
He senses Gohan on the Sacred World of the Kai and teleports there to help Gohan with his training as Gohan asks his father What's he doing here and that his 24 hours are not up yet.