Five years after the events of Dragon Ball, martial arts expert Gokuu has grown up and married Chi-Chi, with a four-year-old son named Gohan. During a reunion on Turtle Island with his old friends Master Roshi, Krillin, Bulma, and others, the celebration is interrupted when a humanoid alien named Raditz not only reveals the truth about Gokuu's past but also kidnaps Gohan.
Faced with Raditz's power, which surpasses anything Gokuu has ever encountered, he is forced to join forces with his former enemy Piccolo to rescue his son. When Gokuu and Piccolo disclose the secret of the seven wish-granting Dragon Balls to Raditz, he warns them that more members of his race, the Saiyans, exist and will not hesitate to seize the Dragon Balls for themselves.
This marks the beginning of Dragon Ball Kai, a saga where Gokuu, his friends, and his family constantly defend the galaxy against increasingly powerful threats. Bizarre, comical, heartwarming, and menacing characters come together in a series of battles that push Gokuu and his allies' powers and abilities beyond anything they have ever known.