In the run-up to the adult division, the junior division of the Tenkaichi Tournament, in which Trunks and Goten are entered, is finally about to start. However, before it does, a special event has been planned. It is a movie, which recreates the scene of Mister Satan defeating Cell. The spectators are worked up into a frenzy, while the Z Warriors are dumbfounded by its shoddiness. And then, Trunks' match begins...
Following Trunks, it was Gohan's turn in the ring. Gohan has a slight case of butterflies but goes on to win as easily as Trunks did. As one might expect, the two of them proceed to win their way forward until the final match pits Trunks against Goten. As the championship match finally starts, the spectators are astonished by the tremendous fight put on by the two of them, something hardly expected from such children!
With the junior division championship at stake, the fight between Trunks and Goten continues. As Trunks strikes with a Ki-based attack, Goten counters with a "Kamekame-Ha," a not-quite Kamehame-Ha! Caught up in the heat of the battle, Goten and Trunks finally end up turning Super Saiyan! Satan is stunned when he sees them, so much like the golden warriors that were present during the fight with Cell. The intense fight ends with the slimmest margin of victory...
Trunks, as champion of the junior division, is allowed to fight Satan in an exhibition match! However, after Satan sees the way he fought during the championship match, he is terrified of Trunks and attempts to lose to him intentionally after a light punch. However, Trunks' "light" punch connects squarely with Satan's face! Meanwhile, having won their way through the preliminaries, Goku and the others encounter the mysterious contestants Shin and Kibit.
The children's division was over, but Goten and Trunks, who wanted to fight in the adult division, launch a surprise attack on Mighty Mask. Doubling up and wearing the stolen mask, they secretly enter the adult division. The contestants come face to face as the tournament lottery is held. As the contestants gather together, including Shin and Spopovitch, who have a surreptitious air about them, the Tenkaichi Tournament adult division at last gets underway!
The first match of the adult division is between Kuririn and Punter. The spectators are confident that the gigantic Punter would win, but with one relaxed blow, Kuririn claims victory. In the following match, Piccolo's opponent is the mysterious man Shin. Sensing his true identity in a way that only someonewho had merged with Kami could realize, he voluntarily steps down from the fight before it even starts. Who is this Shin, exactly?
Piccolo is taken aback to learn that Shin is actually a Kaioshin. In the third match, Videl faces off against Spopovitch. After having lost to Satan at the previous tournament, his strength and personality are both that of a completely different person. Videl's ferocious attacks have no effect, as time and again, he gets back up. Feeling frustrated, Videl accidentally breaks Spopovitch's neck!
Even after having his neck broken, Spopovitch continues to fight, and Videl keeps up her attack, but he shows no sign of being beaten. As fatigue takes its toll on Videl, Spopovitch starts pounding her without mercy! He continues his relentless attack against an opponent who cannot fight back. Watching this brutal battle, Gohan finally turns Super Saiyan and is about to put a stop to it, when Spopovitch's companion, Yamu, steps in...
As Satan worries over his gravely injured daughter, Gohan shows up and gives her a senzu bean, which allows her to recover. Then, as Gohan rushes back to fight in the fourth match, his identity as the Great Saiyaman is revealed. As his classmates cheer him on, the fight between Gohan and Kibit gets started. In the midst of a fierce battle, Kibit whispers something into Gohan's ear...
As instructed by Kibit, Gohan turns Super Saiyan, at which time Yamu and Spopovitch attack him! While Kaioshin keeps Gohan frozen in place, the two of them produce a mysterious weapon, thrust it into Gohan, and after absorbing his energy, fly away. His power drained, Gohan lies motionless on the floor of the ring. Why did Kaioshin assault Gohan? And what was the purpose of the other two's actions?
As Goku and the others follow Spopovitch and Yamu, Kaioshin tells them about the existence of the warlock Babidi and his plans to revive Majin Boo. For this revival to take place, powerful energy is required, and Gohan's energy is being used for this purpose. After finally pinpointing the location of Babidi's base, which is a spaceship, Goku and the others hide behind a bluff to see how things play out. Just then, Babidi shows himself!
The demon king Dabura senses the presence of Goku and the others and attacks! Kibit is defeated, while Piccolo and Kuririn are turned to stone! However, Dabura attacks no further, and with a sneer of confidence, retreats back into the spaceship. In order to put an end to Babidi's scheme, as well as to save Piccolo and Kuririn, Goku, Gohan, Vegeta and Kaioshin enter Babidi's spaceship.
In the spaceship's first combat arena, Battle Stage 1, a fight between Vegeta and Puipui, one of the warriors under Babidi's command, plays out. Vegeta is the superior fighter and demonstrates how mismatched their abilities are. Unable to stand by and watch, Babidi changes the Stage into Planet Zun, a world with ten times the gravity, and a place more favorable to Puipui. In this 10G-gravity environment, in which Puipui is free to move about and strike, what will Vegeta's fate be?
Moving on to Battle Stage 2, a fight between the demon beast Maju Yakon and Goku begins. As Babidi watches the pathetic performance Yakon puts up, he changes the stage to Planet Ankoku, a world without light where Yakon was born. As Goku turns Super Saiyan, the light that he gives off illuminates Yakon as he lurks in the darkness! However, Yakon possesses the ability to devour light as energy!
The battle within Babidi's spaceship continues. Meanwhile, at the tournament grounds, as a result of most of the contestants dropping out of the competition, the tournament's championship is declared to be a battle royale. No. 18 and Mighty Mask, in the form of Goten and Trunks, quickly send all the contestants except for Satan out of the ring to their defeat, and then turn their attention on each other, engaging in an intense battle, all the while ignoring Satan!
No. 18 and Mighty Mask, as well as Satan, who is unable to keep up with the fighting, continue their most unusual championship battle royale. Goten and Trunks find it difficult to defeat No. 18, who is right at home when it comes to fighting, and decide to end the battle in a hurry by turning Super Saiyan and launching a furious spurt of attacks! However, No. 18 sees through their disguise, and with a Kienzan attack, slices their costume clean in half!
With Mighty Mask disqualified, the Tenkaichi Tournament championship battle royale comes down to a one-one-one fight between No. 18 and Mister Satan. As No. 18 immobilizes Satan, she begins whispering something into his ear... At the same time, inside Babidi's spaceship, Dabura, King of the Demon Realm, enters Battle Stage 3. Gohan steps forward to face him to return Kuririn and Piccolo, who had been turned to stone, back to normal!
The one-on-one battle between Gohan and Dabura gets underway! With his fighting skills rusty, Gohan has a surprisingly difficult battle against an opponent who clearly possesses inferior power. When Dabura sees how annoyed Vegeta is at how poorly the fight is going, he interrupts the battle for some reason, and withdraws. Apparently, he has something in mind, making use of the ability that Babidi has to turn those with evil in their hearts into his servants.
As Babidi chants a curse into his crystal ball, Vegeta suddenly begins clutching his head in agony! No sooner does the letter "M" appear on Vegeta's forehead than he starts attacking Goku. Babidi was able to see through the evil in Vegeta's heart, and his desire to fight Goku, and relocates them to the Tenkaichi Tournament ring. Vegeta then releases an enormous energy blast, which strikes the sold-out spectator seats!!
In order to fulfill his secret desire to fight Goku, Vegeta intentionally allowed himself to fall under Babidi's spell. Upon hearing this, Goku makes up his mind to take on Vegeta in a one-on-one battle. Moving their ring to an uninhabited wasteland, the two Saiyans begin their duel. Meanwhile, Gohan and Kaioshin hurry forward toward Babidy, in an effort to prevent Boo from being revived.
At last, the fight between fellow Saiyans, Goku and Vegeta, had begun! Just as Babidi had expected, the fierce mortal combat was playing out. Babidi was allowing the two to fight in order to store up the energy required to revive Boo. Right before his eyes, the energy gauge started rising. Would this go on until, at last, the terrible Majin Boo is restored to life?
The earthshaking battle between Goku and Vegeta continued, and the energy necessary to revive Majin Boo continued to build up. In order to prevent this revival from taking place, Gohan and Kaioshin launch an attack against Babidi and Dabura, but just at that moment, the energy gauge reaches full! Once it does, white smoke begins blowing profusely from the sphere in which Majin Boo is said to be sealed!!
Under no circumstances can Majin Boo be allowed to return! As the suspicious smoke continues to blow out of the sphere, Gohan put his entire body and soul into a Kamehame-Ha blast direct at it. As a result of the blast, the sphere splits into two, revealing that its insides are empty! As an astonished Kaioshin and Babidi look on, the smoke begins to gather overheard, and take on a humanoid form...
The now-revived Boo does not appear to be that evil, and he pays absolutely no attention to Babidi's orders. However, when Dabura makes light of him, he all-too-easily defeats him! Meanwhile, in the faraway wasteland, Goku and Vegeta take notice of Boo's revival and suspend their battle. Vegeta takes advantage of Goku in an unguarded moment, knocking him out, and then flies off alone.
Gohan and Kaioshin both launch an attack against Boo, but even together, they are utterly helpless before him. Then, just as Kaioshin was preparing to accept his death, a spear from Dabura pierces Boo's belly! Dabura begins to attack Boo, hoping to defeat him before he gets a chance to turn his back on them. Just then, Goten and Trunks, who had flown away from the Tournament grounds, find Babidi's spaceship!
An enraged Boo amazingly turns Dabura into a cookie and eats him! The others are stunned at what has just taken place. However, as a result of Dabura dying, Kuririn and Piccolo, who had been turned to stone, are restored. Once again, Gohan and Kaioshin found themselves in a tight spot, faced with Boo's strength, but just then, a huge explosion erupts from within Babidi's spaceship!!
The battle between Boo and Prince of Destruction Vegeta had begun! When Boo takes no damage, even when there are gaping holes opened up in his stomach, Vegeta fights a greater uphill battle than any he has waged before. Using a piece pulled off from his body, Boo wraps his opponent up and attacks! Trunks is unable to sit back and watch as Vegeta falls prey to this bizarre fighting tactic and leaps into the fray!
Trunks launches a surprise attack on Boo, and then, with Goten's help, manages to rescue Vegeta! Meanwhile, although Piccolo is able to defeat Babidi, Boo shows no sign of taking any damage. There is only one way to defeat him. Having made his resolve, Vegeta knocks out the young pair and asks Piccolo to carry them away to a safe location...
In order to wipe Boo from the face of the planet, as well as to protect the ones that he loves, Vegeta focuses all of the Ki that he possesses inside his body and detonates it in a huge explosion! The entire area is engulfed in a brilliant light, and its destructive force causes the entire world to shake. Majin Boo is blown to smithereens, and the pieces are scattered about. Just when it looked as though Vegeta's victory was assured, the fallen fragments begin flying up and merging back together!
A regenerated Babidi begins to overrun the earth with Boo's help. Meanwhile, Bulma, Videl and the others are gathering the Dragon Balls, in order to bring everyone killed by Vegeta at the tournament back to life. The seventh Dragon Ball they need in order to have their wish granted was in the possession of a monster on a desert island. Videl takes on the monster so that she can collect the Dragon Ball!
By using the merging technique of Fusion, which Goku learned from the Metamorian race, it might be possible to resist Boo! The Z Warriors may have been grasping at straws, but the Fusion technique would only work with those of very similar body sizes and strengths. As such, Goku began teaching the process of Fusion to Goten and Trunks, who both had similar builds and unmeasured power!
After Kibit is brought back to life with the power of the Dragon Balls, he locates Kaioshin and Gohan, who had been gravely wounded while fighting against Boo, and takes them both to the Kaioshin Realm. Meanwhile, while Babidi is attacking the earth along with Boo, he begins sending a telepathic message to the whole world. He wants to be told the location of those who defied him--Piccolo, Goten and Trunks!
After Babidi declares that he will destroy one city after another unless the three come forward, the world descends into panic. Meanwhile, in the Kaioshin Realm, Gohan is told of a legendary sword, the Z-Sword, by Kaioshin. It is said that whoever can pull forth the Z-Sword will be given tremendous power! However, in all the generations of the Kaioshin, no one has ever been able to draw it out.
Presumed dead by his friends on earth, Gohan begins his challenge to pull out the Z-Sword. He turns Super Saiyan, and at last, he manages to draw forth the sword that no one else in the Kaioshin Realm has ever been able to draw! Gohan begins his training with the incredibly heavy Z-Sword, in order that he might defeat Boo. Meanwhile, at Kami's temple, Trunks and Goten had begun their Fusion training!
As Goten and Trunks continue their special Fusion training at Kami's temple, they receive a telepathic message from Babidi that he has located Trunks' home! He announces that unless he comes forward at once, it will be destroyed, along with all of Metro West. They will be able to collect the Dragon Balls and wish the city back to life again, but not without the Dragon Radar that is sitting in Trunks' home!
In order to buy enough time to let Trunks go back home and retrieve the Dragon Radar, Goku shows up to confront Majin Boo. To keep Babidi and Boo's attention focused on him, he displays the Super Saiyan levels that were used first to defeat Freeza, then Cell. He then increases his power even greater and transforms to become Super Saiyan 3! With this tremendous power, he attacks Boo and is more or less able to hold his own against him!!
The earthshaking battle between Goku and Boo continues. Trunks finally manages to locate the Dragon Radar, and Goku tells Boo that in two days, someone even stronger than he is will show up. Goku then leaves the area using his Instantaneous Movement. Babidi blames Boo for allowing Goku to get away, at which Boo takes a frightening, drastic measure!
Having killed Babidi, the one who was controlling him, Boo proceeds to start destroying the earth in whatever way his mood dictates! Elsewhere, as a result of having gone Super Saiyan 3 and consuming a great deal of energy, Goku's time in this world has been reduced to just 30 more minutes! Goku hurries to begin teaching Goten and Trunks how to perform Fusion, but the pose they had to go through was unbelievably ridiculous.
Boo was having a free-for-all, from turning people into candy and eating them, to turning them into clay to build himself a house! Goten and Trunks had to hurry if they were going to learn to perform Fusion, but they found the merging pose they were required to make to be so unflattering, they could not get into their training. Unable to bear seeing them like this, Goku persuades them by turning Super Saiyan 3 again. The time for Goku's return to the Other World drew near.
After hearing from Great King Yama in the Other World that Gohan was still alive, Goku sought out his Ki. Relocating himself to the Kaioshin Realm with his Instantaneous Movement, Goku is reunited with his son. Meanwhile, Piccolo, who had been left to carry on the Fusion training, was having difficulty handling the young pair when they refused to listen to him. Elsewhere, Boo begins performing baffling and whimsical deeds, such as heeling the eyes of a blind boy.
As Gohan continues his training, Goku proposes that they see how well the Z-Sword can cut. After slicing a gigantic rock clean in two, Gohan proceeds to take on the challenge of cutting though a block of katchinko, said to be the hardest substance in the universe. However, as the Z-Sword swings into the katchinko, it snaps in half! As everyone is stunned by this unforeseen turn of events, a dubious-looking old man appears behind them...