Time Struggle (特訓成功!!これで終りだ魔人ブウ, Tokkun Seikou!! Kore de Owari Da Majin Bū) is the fourth episode of the Fusion Saga and the two hundred fifty-seventh overall episode in the original dubbed and the uncut Dragon Ball Z series. The episode first aired on February 22, 1995. Its original American air date was October 17, 2002.
Piccolo, Yamcha, Krillin, Android 18 and some others are on the balcony of Kami's Lookout staring at Super Buu, who is staring at the hourglass. Chi-Chi walks up to Super Buu and slaps him and reprimands him for "killing" her first son, Gohan (who is not dead). Super Buu asks if Chi-Chi likes eggs, turns her into one, and then steps on it. Goten begins to cry, but Piccolo tells Goten that they will bring Chi-Chi back to life with the Dragon Balls as soon as Buu is killed. Trunks talks to him about it and cheers him up by saying that they can beat him. In the Hyperbolic Time Chamber, Trunks looks around for food and Goten is training to get revenge on Buu. Trunks soon joins him.
Super Buu eventually lets his impatience get the better of him and breaks the hourglass and demands that Piccolo show him where the "challenger" is. Piccolo complies and the gang secretly follow. Master Roshi takes this opportunity to harass Bulma, and Dende notices that Piccolo is taking the long way. Piccolo contacts the boys telepathically to say that he and Super Buu should be there in a minute, which is 6 hours in the Hyperbolic Time Chamber. Goten complains that he is thirsty, but Piccolo tells him to rest a while. Soon, Super Buu and Piccolo arrive. Trunks and Goten are standing side by side ready to perform the Fusion Dance. They try to fuse, but Super Buu suckerpunches Trunks before he could do anything. He gets back up and tells Buu that they will fight when he says so. They fuse into Gotenks, and Super Buu recognizes him. Gotenks does a few punches at his face, but it does not hurt Buu at all.
- Super Buu kills Chi-Chi, by turning her into an egg and stepping on her.
- The fight between Gotenks and Super Buu begins.
"You savage! Don't you even care that you killed my oldest son?! You look at me when I'm talking to you!"
"Ow, what's wrong with you? You can't just come swinging like that without any warning! Don't you know what a sucker punch is?! That's something only inexperienced fighters do! Do you understand what I'm saying? We're trying to prepare so we can give you a fair fight, so why don't you try some patience?! Now, we're going to power up. You stand there and be quiet and I'll tell YOU when it's time to fight!"
- When Goku was telling Gohan about the Hyperbolic Time Chamber in the episode "Time Chamber", he said that only two people can enter at a time. This proves false, as Goten, Trunks, Piccolo, and Super Buu are all inside the time chamber at once.
- In the Cell Saga, it is stated someone can only stay inside the time chamber for two days. However, Piccolo had already used up his two days inside the chamber, yet in this episode he is able to be inside the of chamber without the door disappearing.
- Mr. Satan, Tien Shinhan, Chiaotzu, Yajirobe, Bulma, Yamcha, Videl, Master Roshi, Krillin, Marron, and Ox-King are now the only known humans on Earth alive, as Chi-Chi was turned into an egg and killed by Super Buu in this episode.
- After Buu breaks the hourglass, he shoots a beam through the lookout near Piccolo's feet. However, a moment after, there is no sign of the hole, yet the fissure he creates after that can still be seen later.
- When Piccolo contacts Goten and Trunks telepathically, the same amount of time appears to pass for all of them. However, due to the time dilation in the Hyperbolic Time Chamber, the duration of his message should be much longer for Goten and Trunks.