The two gunmen proceed to shoot rockets at Buu's house. Hercule runs up to the hill they're on and pounds each of them. Buu is able to heal the dog, and the three friends continue having fun. Buu rebuilds his house to look like the dog. While Hercule is cooking a meal for Buu, one of the gunmen sneaks into Buu's house and shoots the World Champ. Buu starts to lose control of himself. After he heals Hercule, he instructs him to get away. Buu begins giving off more steam than ever, and the steam is congealing in the sky. It forms the evil side of Buu, a tall, thin, gray version of Majin Buu. Evil Buu flies over to the gunman and blasts him into nothing.

Evil Buu and Good Buu begin to fight, and it's clear that Evil Buu has the advantage. Good Buu tries to turn his opponent into chocolate, but Evil Buu deflects the ray back at Good Buu, who becomes a piece of chocolate. Evil Buu consumes the chocolate, and transforms into Super Buu, a bulkier, pink version of Evil Buu. Super Buu blows up the other gunman, and spies another person hiding nearby. He is about to destroy the other person, when he realizes that it's Hercule. He spares his friend, and flies off. He arrives at Dende's lookout.

Buu demands to fight Gotenks, but Piccolo knows that the boys aren't ready. To buy time, he tells Buu that he can spend a day killing the rest of the people on earth. Buu starts walking around the edge of the lookout, and Piccolo uses this time to tell Krillin to wake up the boys and get them into the Hyperbolic Time Chamber to train. Buu completes his walk, and raises up his arm. Millions of energy blasts start flying out of his hand down to earth. After the Human Extiction Attack is finished, only Hercule, the dog, Tien, and Chiaotzu remain, as well as the fighters on the lookout. Piccolo asks for Super Buu to wait for one hour, and Videl agrees. Buu complies, because Videl is the daughter of Hercule.

Chi Chi slaps Super Buu for killing Gohan, and in retaliation, Buu turns her into an egg and crushes her. Goten vows to train as hard as he can for what Buu did to his mother. The boys enter the Hyperbolic Time Chamber and begin to train. Buu's patience wears off after thirty minutes, and he demands to fight his opponent right now. Piccolo decides to take Buu to the Chamber, but he walks as slowly as he can, giving the boys as much time as possible. He mentally warns them that Buu is coming so they can rest up in time. The boys seem to have developed a few new tricks, and they have planned their fight with Buu. Finally, Piccolo and Buu arrive at the chamber, and Goten and Trunks fuse together.

Super Buu and Gotenks begin to fight, and Gotenks decides to use some of his special moves. The problem is that these moves are totally ineffective, not to mention they have ridiculous names, like the Screaming Angry Wombat. After it is clear that these moves have no effect, Gotenks talks strategy with Piccolo. He then creates a ring of energy and traps Buu inside. After a brief struggle, Buu is able to break the ring. The two then do a bit of real fighting. Gotenks decides to use another one of his special moves, called the Super Ghost Kamikaze Attack. He spits out a ghost of himself, and plans to use it against Buu.

Gotenks creates ten ghosts that detonate with explosive force when they are touched. He sends all but one at Super Buu, and they reduce him to a deformed puddle of his former self. Gotenks sends the final one down Buu's mouth, blowing him into tiny pieces. Gotenks and Piccolo destroy all of the pieces, but the smoke coming off of the pieces gathers above their heads and reforms Super Buu. To play up the drama of the situation, Gotenks acts like he's out of ideas, and Buu begins beating up on the fused Saiyan. Suddenly, Piccolo destroys the door to the outside world, which traps the three of them in the Chamber for all eternity.

Heartbroken at the idea that he will never eat candy again, Super Buu lets out a powerful scream that rips a hole in the dimension. He jumps through it, and the hole closes before Piccolo and Gotenks can get through. Back on the outside, Buu is hungry, and so he turns everyone at the lookout into chocolate. Piccolo and Gotenks have been attempting to scream loud enough to create an interdimensional hole like Buu did, but they've seen no success. Gotenks decides to play his trump card, transforming into a Super Saiyan 3. This gives him the power Buust needed to rip a hole for he and Piccolo to jump through. Back at the lookout, Buu tells Gotenks that he ate all of his friends, and enraged, Gotenks promises Buu that he'll pay for each one.

Gotenks and Super Buu begin to fight, and the collateral damage from the battle begins to destroy the lookout. Buu slams Gotenks down through the lookout itself. Down on earth, Gotenks tries another Super Ghost Kamikaze attack, but it once again fails. Buu lands a powerful hit on Gotenks that sends him flying back into the lookout. Buu then forms himself into a ball, and begins repeatedly shooting himself at the lookout until all that's left is rubble floating in the air. While still in a ball, Gotenks is able to trap him in a little sphere. He and Piccolo then play some volleyball with Buu, and Gotenks spikes him down to earth. Just when it seems like Buu is dead, a powerful blast of energy comes from the crater. Gotenks only has a few minutes until he separates.

Gotenks and Buu continue their fight. Gotenks seems to be wearing Buu down, and he has the upper hand in the fight. Just as he's about to hit Buu with his final move, Gotenks returns to normal from his Super Saiyan 3 form. The power was too much for him to sustain. Buu begins beating up Gotenks, who is now much weaker. Gohan has finally finished his training, and is ready to return to earth. After saying goodbye to Goku for the last time, Kibito takes him back, and Gohan asks him to change his clothes. He's now wearing clothes just like Goku. He's arrived just in time, because Gotenks has separated.

Gohan arrives at the scene, and everyone is shocked at how much power he has. As Gohan begins pounding him, Buu steps up the intensity, but Gohan still has the upper hand. He is easily picking Buu apart.

Realizing that he's totally outmatched, Buu decides to self-destruct, hoping to take Gohan with him. Gohan is able to escape, and he takes the others with him. After the detonation, there is no sign of Buu, but Gohan is sure that he's still around. They suddenly sense Dende's energy signal, and they go to find him. On the way, they pick up Hercule and the dog, Bee. Dende explains that as Buu was escaping through the dimensional hole, Mr. Popo threw him off of the lookout, because without Dende, there are no Dragon Balls. Buu tracks them down, but instead of having a rematch with Gohan, he calls out Goten and Trunks.

Unknown to the others, Buu secretly separates part of his back, and the two pink blobs creep around behind the others. As soon as Goten and Trunks fuse, one of the blobs encases the Saiyan. Piccolo, too, has been covered by a pink blob. Buu calls each of the blobs back to him, and they combine to form a Super Buu that's even stronger than he was before. Buu and Gohan start to fight, and it's clear that Super Buu has the advantage. Gohan seems unable to keep up with Buu's new speed and strength. Buu taunts Gohan by telling him what his three friends that were absorbed think of him.

Gohan is no match for the new Super Buu. Buu now possesses new skills, such as the Super Ghost Kamikaze Attack, and the Special Beam Cannon, each of which he uses on Gohan. He is about to finish Gohan, when Bee comes running up. Hercule tries to save Bee, but is incredibly weak. Buu is about to blast each of them when Gohan saves them. Buu then uses Gotenks' Ring Binding trick on Gohan. He then aims a Kamehameha wave at him, but Gohan is able to summon enough strength to escape in time. Meanwhile, in Other World, King Yemma decides to send Vegeta back to earth to fight Buu. On the world of the Kais, the Elder Kai decides to give his life to Goku so he can fight Buu. The now deceased Elder Kai gives Goku his earrings. If Goku and Gohan each wear one, they will fuse together.

Elder Kai tells Shin and Kibito to try a fusion with their earrings, but only after they fuse together does he reveal that it is a permanent fusion. Dende heals Gohan's injuries, so to prevent this from happening again, Buu creates a giant energy ball and aims it at Dende. Just before it hits, it is blasted out of the way by Tien's tribeam, who has arrived just in time. Buu tries again, but Goku suddenly appears and sends a disk of energy at the monster. It cuts off his legs and part of his head. His legs give Tien a crushing kick, and then return to Buu. Goku throws Gohan the other earring, but his aim is off. Goku goes Super Saiyan 3 to hold off Super Buu while Gohan serches for the earring. Suddenly, Gotenks' fusion wears off, and Buu loses most of his power. To make up for this, the part of Buu's head that was cut off suddenly engulfs Gohan, just like Piccolo and Gotenks. He merges with Gohan, and is now even more powerful than before.

Buu gives Goku some time to find someone to fuse with. He considers Dende and Hercule, but neither of them would be any help. He suddenly senses that Vegeta has returned, and uses Instant Transmission to find him. Dende then heals Tien. After he finds him, Goku tries to convince Vegeta to fuse with him, but Vegeta is angry because he knows Goku was holding back his Super Saiyan 3 technique when they fought. They each try to take on Buu, but are clearly outclassed. Goku tells Vegeta that Buu absorbed Bulma, and asks him to put their differences aside to save their race. Vegeta finally agrees, and only when he puts the earring on does Goku mention that the fusion is permanent.

The fused Goku and Vegeta names himself Vegito, and begins to fight Buu. He clearly is far superior to even the new Super Buu. In Other World, Bulma, Videl, Chi Chi, and Dabora are looking for Gohan, whom they believe to be dead. Dabora has changed his ways, and is trying to help them. Back on earth, Dende and Hercule arrive at the battle scene, just as Buu has decided to destroy the earth. He creates a massive ball of energy, and throws it towards the earth. Vegito easily catches it, and deflects it back out into space. Buu claims that he has yet to fight at his full power. Vegito says the same, and powers up to a Super Saiyan.

Vegito continues to thrash Majin Buu. Buu tries to hide himself with his own steam, but Vegito still beats up on him. On the Grand Kai's planet, Krillin and Yamcha are training with King Kai. Back on earth, Buu is starting to become desperate. He liquifies himself, and shoots down Vegito's mouth. While inside Vegito, he tries to control the Saiyan, but Vegito uses his energy to isolate Buu and beat up on him. Buu is forced to exit Vegito's body. He begins to freak out, and the universe itself starts to rip. Vegito tries to stop him, but Buu has put up a shield around himself. After a long struggle, Vegito breaks through the shield and stops Buu.

Vegito and Buu continue to fight, and Vegito is still far more powerful than his opponent. He repeatedly dominates Buu, which makes Buu angrier and angrier. Vegito is just toying with him. Buu hatches a plan, and calls Vegito out. Vegito comes closer, and Buu turns him into candy. Meanwhile, Videl, Bulma, Chi Chi, and Dabora continue their search for Gohan. Videl still doesn't believe that Gohan is dead.

Before Buu can eat it, the candy made of Vegito begins to fight back. It is just as powerful as Vegito was, except it is too small for Buu to hit. Buu changes it back into Vegito, who then proceeds to beat him up. Vegito literally starts tearing Buu apart. He gives Buu ten seconds until he destroys him, and during this countdown, Buu notices a part of himself that Vegito tore off down on the ground. This part rises up behind Vegito, and before he reaches ten, he is engulfed by the pink blob. Buu has absorbed Vegito.

After absorbing Vegito, Buu has not taken on any of his characteristics, because he hasn't digested him yet. Inside Buu, Vegito still exists. He put up a barrier during the absorption, because he let it happen on purpose. Once he dispels the barrier, Vegito splits back into Goku and Vegeta. Vegeta crushes his fusion earring, citing that once they free their absorbed friends, Buu will lose most of his power. As they journey through his innards, they find some tiny green pieces of slime. The slime starts to attack, and it completely covers Goku. Suddenly, a giant worm appears, ready to eat Goku.

Goku shakes off the slime, and blasts the worm. The worm then calls his father, but instead of eating Goku, the father yells at his son. Goku and the worm become friends, and the worm points them in the direction of the four they're looking for. Goku and Vegeta arrive in Buu's head, where they encounter what appear to be Piccolo, Gohan, and Gotenks. These three begin attacking Goku and Vegeta, and even though Goku and Vegeta are winning the fight, their attackers don't take on any damage. Buu goes to a bakery and begins to eat some cake, which causes what appeared to be Piccolo, Gohan, and Gotenks to turn into cakes. They were just Buu's thoughts. Goku and Vegeta finally find their four friends, who are trapped in cocoons, unconscious, but alive.

Goku and Vegeta cut down their four friends, and as they do, Super Buu regresses to his earlier form. Dende and Hercule continue to follow Buu. Back inside Majin Buu, Goku and Vegeta also find the original Majin Buu. They read his thoughts to find out what happened to him. Suddenly, a thought form of Buu himself appears. The two join forces to defeat it, but once they do, another one appears. They realize that this is a battle they can't win. Buu finally decides that he's had enough, and he tries to absorb Goku and Vegeta.

Goku saves Vegeta from being absorbed. As Vegeta recovers, Goku continues to fight the thought form of Buu. Goku is rapidly losing energy, and just as Buu is about to destroy him, Vegeta cuts down the pod containing the original Majin Buu. This causes Buu to go mad, and so Goku and Vegeta grab the four pods and try to make their escape. On their way through is body, they notice one of the tunnels that leads to one of the holes in Buu's body where the steam escapes. They are able to fly out through here, and when they emerge on the other side, all six of them regain their normal size. As Goku and Vegeta set the pods down, they notice Buu undergoing a change. He shrinks into Kid Buu.

Supreme Kai explains to the Elder Kai that there were once five Supreme Kais. Four of them ruled over a quadrant of the universe, and the fifth was their leader. He says that Kid Buu was his original form. North and West Kai perished against Majin Buu. South Kai was absorbed. The leader, Dai Kaio, was also absorbed, but this absorption changed Buu into the fat, happy Buu that came out of the ball. The absorption of the Kais weakened Buu. Back on earth, Kid Buu creates a massive ball of energy and throws it at the earth. Goku and Vegeta try to grab their sons and Piccolo, but are only able to grab Dende and Hercule. Goku Instantly Transmits to the world of the Kais.

Buu reforms after the destruction of the earth, and goes on a rampage throughout the galaxy. He goes from planet to planet, looking for Goku and Vegeta, and then destroys the place when he doesn't find them. He goes to the Grand Kai's planet, and starts to destroy everyone there. Supreme Kai offers Goku and Vegeta his fusion earrings, but they both refuse them. They raise their power levels so Buu will know where to find them. Buu appears on the world of the Kais.

The Supreme Kai transports himself, Dende, and the Elder Kai to a distant planet so they will be out of Goku and Vegeta's way. Unfortunately, they forget to take Hercule and Bee along. Goku and Vegeta play janken to decide who will fight first, and Goku wins. He powers up, and starts beating on Buu. He blasts him apart, but he reforms. Buu creates another massive energy ball and throws it down at the planet. Goku is able to deflect it, but Buu guides the ball back around and into the planet. Powerful earthquakes rock the surface of the planet, leaving the ground ragged and uneven. Goku decides to power up to Super Saiyan 3.

Goku and Buu continue to fight, each taking powerful blows from each other. Buu tries his ball trick again, and hits Goku hard. Goku puts all of his energy into a massive Kamehameha, but Buu just reforms afterward. Goku powers down to his normal state and collapses. Vegeta steps in, but he is no match for Buu. Buu cleans his clock, and just as he's about to give Vegeta his finishing blow, Goku pushes him out of the way. He then powers back up to Super Saiyan 3 and continues their furious fight. Vegeta reminisces about all of the fights he and Goku were in. He finally admits that Goku is better.

Goku continues to fight Buu, and he seems to have the upper hand. He deals out a lot of damage to Buu, but as the fight goes on, his hits become weaker and weaker until they have no effect at all. He tells Vegeta that it's his turn, but Vegeta declines, citing that he is no match for Buu. He tells Goku that he's better than him. Goku says that he nees one minute to power up enough to destroy Buu. While Goku is powering up, Vegeta steps in, knowing that if he dies again, he will no longer exist in any form. Buu thrashes Vegeta, but every time he gets knocked down, he gets up, ready for more. Buu stretches out his arm, wraps it around Vegeta's neck, and begins choking him. It's been more than one minute, but Goku still has not generated enough power.

Buu is about to blast Vegeta, when suddenly Hercule starts to taunt him. Buu lets Vegeta go, and turns his attention to Hercule. The world champ, thinking that it's all a dream, tries to destroy Buu, but is obviously ineffective. Buu winds up to punch him, but suddenly stops. He wrestles with his mind for a moment, and then spits out the fat form of Buu, who, though not part of his physical being, was still inside of Kid Buu. Hercule tries to beat up Buu again, but fails. Buu sends a blast toward Hercule, but it is knocked away by the old Buu, who has regained consciousness. Meanwhile, Goku still can't gather enough energy. He starts losing energy, and falls to the ground in his normal form.

The old Buu is no match for Kid Buu, who begins to wail on him. Hercule continues to try to help the old Buu, but is ineffective. Vegeta suddenly comes up with a plan. He communicates with Dende, telling him to go to the new planet Namek and gather the Dragon Balls. The Supreme Kai and the Elder Kai take him there, and the Namekians are waiting with the seven balls. Porunga is summoned, and Vegeta tells Dende his two wishes: bring back the earth and restore it to its original state, and bring back all of the non-evil people that died since the morning of the World Martial Arts Tournament. These wishes are granted, and even Vegeta himself comes back to life. He finally reveals the main part of his plan to destroy Buu: the Spirit Bomb.

The people of earth come back to life, including the Z Fighters and their friends. Goku gets into position to create the Spirit Bomb, and with the help of King Kai, Vegeta speaks to the entire population of earth. He tells them what's going on, and that do defeat Buu, they need to raise their hands up and offer their energy. Only Goku and Vegeta's family and friends comply. No one else is willing to listen to a mysterious voice from the sky. Vegeta repeatedly pleads with the earthlings, but to no avail. While this is going on, old Buu is buying them time by fighting Kid Buu, but it's not going well. Goku hasn't gathered nearly enough energy to destroy Buu.

Vegeta continues to plead with the people of earth, but no one will listen to him. Old Buu has finally lost all of his energy, so Vegeta is forced to fight Kid Buu. He is no match for him, and gets pounded. Now Goku asks the earthlings to raise up their arms, and small pockets of people who recognize his voice do so, but the vast majority remain uninterested. Piccolo, Gohan, Goten, and Trunks spread out into the city, hoping to convince people to raise their arms. Hercule has finally had enough, and he speaks to the people of earth. When they hear the familiar voice of the World Champion, all of the people of earth raise their arms and offer their energy. The Spirit Bomb is finally ready.

Goku is ready to throw the Spirit Bomb, but Vegeta is in the way, and, despite Vegeta's pleas otherwise, he refuses to take out Vegeta along with Buu. Suddenly, old Buu gets up and holds Kid Buu down long enough for Hercule to pull Vegeta to safety. Old Buu is kicked aside, and Goku throws the Spirit Bomb. It hits Kid Buu, but he starts pushing it back. Goku uses all of the energy he has trying to push it back into Kid Buu, but Buu is too powerful. Vegeta suddenly remembers that they still have a third wish with Porunga. He instructs Dende to wish for Goku's power to be normal again. The wish is granted, and Goku is able to force the Spirit Bomb back at Majin Buu. As he does so, he silently wishes that Buu had been a better person, and hopes to fight him some day in the future. The Spirit Bomb hits with full force, driving Buu into the ground. Majin Buu is finally dead.

The Supreme Kai brings Dende back to the world of the Kais. Dende heals Vegeta and Goku. Hercule finds the body of old Buu, and asks Dende to heal him. Vegeta won't let him, and plans to destroy him. He says it is too dangerous for any form of Majin Buu to exist, but Hercule continues to plead with him. Goku takes Hercule's side, explaining to Vegeta that it was old Buu who saved Vegeta's life right before Goku threw the Spirit Bomb. Vegeta reluctantly agrees, and Majin Buu is healed. Supreme Kai takes them all back to Dende's lookout, where they reunite with friends and family. Goku tells his family that Elder Kai gave him his life, so he can stay on earth for good. Four months later, they use their remaining wish with Shenron, asking him to erase the memory of Majin Buu from the mind of everyone on earth, so that the good Buu can assimilate into society. Life finally returns to normal on earth.

Bulma has invited everyone to a barbecue at Capsule Corporation, and Goku's family is ready to leave. The only problem is that Goku is nowhere to be found. Frustrated, Chi Chi and the boys leave without him. While everyone's having a good time at the party, Goku is out on a mountaintop, looking after some eggs that are ready to hatch. He protects them from the storm and from predators. After they hatch, he finally arrives at the party, to the delight of everyone.

Five years have passed, and Goku is training with Goten when Bulma and Vegeta show up. Goku says that he and Goten will be entering the World Martial Arts Tournament, so Vegeta says that he and Trunks will do the same. The day of the tournament comes, and old friends catch up. Everyone has arrived to watch. Gohan, who is now married to Videl, has decided not to enter, but his daughter, Pan, will fight. Since there is no junior division, she will be fighting with the adults. Hercule and Buu will be fighting, however, and Goku says that there is someone who is 100% human that can threaten to beat Goku and Vegeta.

The seeding draw for the tournament begins, and Goku has Majin Buu use his magic to rig it so that he faces the powerful mystery fighter he had talked about. In the first match, Pan faces Wild Tiger, and the four-year-old easily dispatches with him. Next up is Goku vs. Uub. Uub is the reincarnation of Buu. King Yemma apparently heard Goku's wish right before Buu was destroyed, and he reincarnated Buu as a good person, named Uub. Uub is apprehensive, so to bait him into fighting, Goku resorts to taunting the young boy. After a particularly nasty insult and a kick to the face, Uub has snapped, and is now ready to fight.

Goku and Uub begin to fight, and it's clear that Uub doesn't know much about fighting. But as the match goes on, he learns more and more, and is able to go toe to toe with Goku. Uub nearly falls out of the ring, but Goku saves him from hitting the ground. He realizes that Uub doesn't even know how to fly, so he decides to live with Uub in his village and train him. Despite his friends and family pleading with him to stay, he flys away with Uub. Goku is training Uub to defend the earth when he's gone. He hopes one day, when Uub's training is complete, to have a real all-out match with him to test their power.