Seven years have passed since the Cell game. Gohan starts attending Orange Star High School in Satan City (yes, they named the city after Mr. Satan). There he meets Mr. Satan's daughter Videl. She is a crime fighter and is always there when something bad happens in Satan City. Gohan had gone to Satan City a couple of times before he started school, and each time he went he had to save the city from some criminals. Instead of having everyone find out who he was, he would turn into a super saiyan and then he got the name of "The Golden Warrior". Videl arrived once to the crime scene too late and a man that saw the whole thing told Videl that the person who saved the city was a young man with blonde hair, the school emblem, white shirt, black vest, and orange pants. So Videl goes to school and asks the guys with blonde hair if it was them. Then she accuses Gohan that it is him because he was wearing what the man had described, but he reminds her that he doesn't have blonde hair. She then tells him that she was wrong about him and that she didn't mean to accuse him, but she still has a suspicion because she remembers seeing some men that were able to turn their hair blonde during the Cell tournament from some of her dad's old tapes, but her dad had told her it was just a dumb trick, so she forgets the idea.
Since Gohan finds out that she is going to discover him, he goes to Bulma to ask her to make him something. She does it and he is now the Great Saiyaman. In his disguise he saves a lot of people and now Videl wants to find out who the Great Saiyaman is because he saves her two times. She finally does find out Gohan's secret, by a scar that Gohan had on his face, and begs him to teach her how to fly. She also makes Gohan join the Tenkaichi Budokai so that they can fight against each other in the final, and then he finally agrees. About this time Gohan goes to Capsule Corp and asks Bulma to make him something else for his head so that he will be able to fight in the tournament, because the helmet he had now was not allowed. When Vegeta hears that Gohan was joining the tournament he tells Gohan that he too will enter because he wanted to see if he was now stronger than Gohan. A voice comes out of nowhere and says that he too is joining the tournament. It's Goku! Goku tells them that he will be granted one day to fight in the tournament and Gohan goes and tells the other Z warriors.
Krillin was living with Kamesenin along with his wife 18 and his daughter Marron. When 18 finds out that the tournament winner would receive one million dollars, she insists on joining and starts training right away. Piccolo is living with Dende at the Kami-tower along with Mr. Popo and says that he too will join. In the meantime, Goku starts to train in heaven. Gohan goes home and tells his mom and we find out that Chi-Chi has a second son named Goten that was born a couple of months after the Cell tournament. Gohan tells his mother that Goku will be coming and she gets so happy. She is even happier because she will win a lot of money, because she says that Goku and Gohan are sure to win first and second place. She allows Gohan to miss school to train and so Gohan begins his training.
Goten tags along and when Gohan asks him to help him he shows Gohan that he too can turn Super Saiyan. Gohan is so surprised and happy. He didn't think that Goten could turn Super Saiyan at such an early age. So now Gohan trains with Goten, but there is a problem. Goten does not know how to fly. Being a nice brother, Gohan tells Goten that he will teach him to fly. At this moment, Videl comes in and reminds Gohan that he promised her that he would teach her to fly. So the next day they start their flying lessons. Goten gets it right away and Videl learns a little while afterwards. At the same time Vegeta too trains in the time room with Trunks. He was training under a lot of gravity and it was too much for Trunks. Vegeta asks him to leave because he would only get hurt, but then Trunks turns Super Saiyan and starts running all over the place. Vegeta is very surprised and finds out that Goten too can turn Super Saiyan.
The day of the tournament finally arrives, and of course, so does Goku. The children's tournament begins first. Goten gets runner-up and Trunks wins. Being the winner, Trunks gets to fight against Mr. Satan. With one simple punch, Trunks wins, and Mr. Satan says he "let" Trunks win. When the tournament for the adults is about to begin, two strange men appear before Goku, and both of them are finalists in the tournament. The first fight is between Krillin and Punter, and of course Krillin wins. The next fight is between Piccolo and Kaioshin, and for some odd reason, Piccolo refuses to fight him because of the major difference in "dimensions". After the fight Piccolo asks Kaioshin if he is the Grand Kaiosama, but Kaioshin tells Piccolo that he is not, that he is the Supreme Kaiosama, which is the God that the Kaios and the Grand Kaiosama worship. At this Piccolo is very astonished, but promises not to tell anyone. The next fight is between Videl and Supopobichi. Supopobichi wins. It's Gohan's turn to fight next and it is against Kibito. Kibito asks him if he would turn Super Saiyan for him, and so he does. At that moment, two men with "M"s on their foreheads, named Supopobichi and Yamu, steal Gohan's energy. The two run away and head toward a space ship. While Gohan is still unconscious, Kaioshin follows the two men and then so does Vegeta, Goku, Krillin, and Piccolo (just a few moments before, Piccolo told them who Kaioshin was). Before they leave, Kibito reassures Goku that he will heal Gohan, and so Goku leaves Gohan to Kibito. Kibito does exactly what he said; he gives Gohan's energy back, and even a little more than what he had before. While Goku and the others are following Kaioshin, Kaioshin tells them about the story of Buu and Babidi. How Babidi's father, Bibidi, had killed the other Kaioshin. How Bibidi was killed and how Buu got trapped in an egg. After Gohan gets his powers back, him, Videl and Kibito try to catch up with the others. At the same time Kibito is telling them the same story.
Since most of the participants left, and the tournament must go on, some fights continue and we get to the finals. It is between 18 and Mighty Mask (which is Goten and Trunks in disguise) to see who gets to fight the almighty Mr. Satan. 18 figures out who Mighty Mask is and so Mighty Mask is disqualified. 18 is up to fight Mr. Satan. Mr. Satan is very scared of her because he saw the fight against Mighty Mask and knew what she could do. So 18 takes advantage and tells him that she will let him win if he gives her 2 million dollars (remember, the prize was one million), so Mr. Satan accepts and he wins the tournament. At the same time, Goku and the rest enter the ship, while Piccolo and Krillin stay outside because Darbura turned them into stone with his spit. As they enter different stages they have to pass some obstacles, like fighting some bad guys, but of course the warriors win all of them. But then it's Gohan's turn to fight (he had not trained at all) and he is up to fight Darbura (Babidi's main guy). The fight seems pretty even and is barely starting. Darbura stops fighting and reports to Babidi. He tells him that he has a plan.
Since he had felt that Vegeta was evil (he kept screaming at Gohan and Goku), he wanted him to be on their side. And then Babidi possesses Vegeta and he becomes Majin Vegeta (with an "M" on his forehead). All Majin Vegeta wants to do is fight Goku. They are transported onto the tournament grounds (the final battle had just finished) and Vegeta blows up 2 sections of it, killing a lot of innocent. This upsets Goku very much and he finally agrees to fight him. In this conversation with Vegeta, Goku discovers that he let himself be possessed by Babidi on purpose, because this was the only way to get Goku to fight against him because he (Goku) had only one day of life on Earth. In order for no more people to be killed, they are transported to another place where there are no people and the fight begins there. Meanwhile Gohan and Kaioshin enter Babidi's ship.
The intense fighting between Vegeta and Goku gives Buu enough energy to be revived. So Buu finally wakes up and now Vegeta finally realises good always triumphs over evil and self-destructs in hope to kill Buu. Goku then heads to battle against Buu; Goku turns SSJ2, then SSJ3 but he still can't defeat Buu. Later, Gohan heads to the Kaio-shin's planet for training.
Before Goku's time is up on Earth he teaches Goten and Trunks the fusion technique, then Piccolo trains them so they can be strong enough to beat Buu. Soon after Goten and Trunks fuse to become Gotenks, later Gotenks turns SSJ1 and SSJ3. Gotenks is defeating Buu, but Buu absorbs Gotenks and becomes a lot stronger.
Kaio-shin sacrifices his life so Goku can live. Goku, now alive, teleports to the battle. Soon after King Yama grants Vegeta life to fight Buu. When Goku arrives to the scene he tells Gohan to fuse with him, Goku then throws a fusion earring at Gohan. Gohan drops the earring and Boo absorbs Gohan. Then Vegeta comes to the scene and he doesn’t want to fuse with Goku. But after being convinced, Vegeta fuses with Goku to become Vegeto. Vegeto defeats Buu, but lets himself get absorbed to rescue their friends (this wears the fusion off). They rescue Goten, Gohan, Trunks, and Piccolo through Buu's pores.
All of the energy that Buu has taken was gone and he restores back to his normal form, but then Buu destroys the Earth. Kaio-shin teleports to help Goku teleport Vegeta, Goten, Trunks, Piccolo, Satan and Dende to Kaio-shin's planet. Goku and Buu start to fight, Goku starts to get beaten up badly. Vegeta jumps into the battle so Goku can create a Genki-Dama (spirit bomb).
The Namek Dragonballs are gathered to wish back the Earth and to wish back everyone killed by Buu. The third wish is stored for later use. Goku's Genki-Dama is ready, Goku throws it and Buu pushes it back. Vegeta tells Dende to wish back all of Goku's strength back. Now with all his strength restored, Goku throws back the Genki-dami at Buu. Buu can't counter it so he is killed. Then, Vegeta is amazed by Goku’s strength and then admits that Goku is the strongest. He then respects Goku.
Ten years after the battle against Buu, Buu is reincarnated into an evil cleansed form called Ubuu (young boy). Goku decides to train him since he has great potential. Gohan and Videl get married and have a daughter named Pan. This is the end of Dragonball Z.
