Prologue to Battle! The Return of Goku! (闘いの幕開け! 帰ってきたぞ孫悟空, Tatakai no Makuake! Kaette Kita zo Son Gokū) is the first episode of Dragon Ball Z Kai and the first episode of its version of the Vegeta Saga. The episode first aired on April 5, 2009. Its original American air date was May 24, 2010. Its Dragon Ball Z counterparts are "The New Threat" and "Reunions". This is the first episode in the Dragon Ball anime aired for the first time in twelve years since the final episode of Dragon Ball GT in 1997.
The episode begins with a flashback of the Genocide of the Saiyans and the destruction of Planet Vegeta at the hands of Frieza, and the upbringing of Goku on Earth, as depicted in the original Dragon Ball series. Five years have passed since Goku's victory over Piccolo at the World Martial Arts Tournament, and he has since married Chi-Chi. with whom he had a son named Gohan named after Goku's grandpa, Grandpa Gohan.
Goku and Gohan are heading towards a reunion with Goku's friends at the Kame House. Elsewhere, a space pod crashes on Earth. A man with a Battle Armor emerges from the vessel and flies off to scout out a powerful lifeform. He locates it with the help of a scouter apparatus located on his eye. Piccolo is nearly killed by the stranger, but this is averted when the man leaves to scout out a more powerful lifeform. The other strong lifeform is Goku, who, at Master Roshi's house, introduces his son to Roshi, Krillin, and Bulma. The stranger arrives and speaks to Goku in a familiar manner.
Differences from Dragon Ball Z
- Most of the filler scenes of Gohan were removed.
- The point where this episode ends is the half-way point of "Reunions".
- Bardock's Final Spirit Cannon has been remade.
- The destruction of Planet Vegeta has been entirely re-animated to look more detailed.
- During the flashback, Piccolo's blood has been changed from red to purple.
- In many scenes, Nicktoons has changed blood with spit. Master Roshi's beer has been changed to pure light. The farmer's cigarette and the brand name of his truck has been totally removed.
- In this episode, Frieza is voiced by Linda Young, but in the Frieza Saga, he is voiced by Chris Ayres. Sean Schemmel and Christopher Sabat revealed in an interview that this is because their original intention was to bring Linda Young back as Frieza, but the script changes would have required Young to speak rather quickly, something she was likely not capable of, and so they cast Ayres to replace her. Of note, Frieza does not speak any dialogue in this episode, instead only laughing.
- In the Japanese version, while the original broadcast of this episode featured Kenji Yamamoto’s musical score, the background music in all subsequent re-airings, as well as airings of all Dragon Ball Kai episodes have been replaced by Shunsuke Kikuchi’s original musical score from Dragon Ball Z due to allegations of musical infringement. Kenji Yamamoto is credited as the series’ musical composer, although Shunsuke Kikuchi is credited as such in all subsequent re-airings and home video releases featuring his replacement score.
- The uncut broadcast on Adult Swim's Toonami block, accidentally retained Yamamoto's score however.
- In the Japanese version, the word “paradise” was misspelled as “paradice” in the opening theme lyrics of this episode’s initial broadcast. This error did not appear in any other subsequent episode and has since been corrected for all re-airings and home video releases of this episode.
- This episode begins with a recap of Son Goku’s origin and growth on Earth, which were not originally shown in the series. Scenes from the first Dragon Ball Z TV special are also shown, along with brief clips from throughout the Dragon Ball series. These clips highlight most of the major events from the series, but for some reason skip over both the Red Ribbon Army saga and Fortuneteller Baba sagas.
- In the Japanese version, the name of Master Roshi’s voice actor Masaharu Satō, was accidentally misspelled in the ending credits as “Satō Masahiro”. Thankfully this was the only misspelled credit seen in the entire series.