Five years have passed since the events of Dragon Ball. Gokuu, a martial arts expert, is now a grown man, happily married to his wife Chi-Chi, and they have a four-year-old son named Gohan. One day, while Gokuu is attending a reunion on Turtle Island with his old friends like Master Roshi, Krillin, Bulma, and others, their joyous gathering is disrupted by the arrival of a humanoid alien named Raditz. Raditz not only unveils the hidden secrets of Gokuu's past but also abducts Gohan.

Raditz possesses an unprecedented level of power, forcing Gokuu to form an unlikely alliance with his former rival, Piccolo, to rescue his son. During their confrontation with Raditz, Gokuu and Piccolo disclose the existence of the seven mystical Dragon Balls, which can grant wishes. Raditz reveals that there are more of his kind, the Saiyans, who are eager to harness the power of the Dragon Balls for their own purposes.

This marks the beginning of the Dragon Ball Kai saga, a tale in which Gokuu and his friends and family are continually thrust into battles to defend the galaxy against increasingly formidable adversaries. Throughout this journey, a colorful cast of characters, ranging from bizarre and comical to heartwarming and menacing, unite in a series of epic battles that challenge the limits of Gokuu and his friends' powers and abilities like never before.