Even Further Activity! The Turbulent Tenkaichi Budoukai (Localization name is A New Leap Forward! The Chaotic Tournament!) covers chapter 6 to 8 of the video game Dragon Ball Z: Attack of the Saiyans. It begins in the World Tournament, three after the defeat of the evil Mazoku, King Piccolo, and the Z Fighters meet his son and reincarnated form, Piccolo Jr.
It has been three years since Goku went out to train with Kami and the Z Fighters had left to train. The Budoukai Arena is under heavy rain, and Master Roshi, accompanied by Launch, arrives with Oolong. Bulma arrives, and soon Goku does too, and, much to the protagonists' surprise, is an adult. Tien, Yamcha, and Krillin arrive, and they sign up for the Tenkaichi Tournament.
Goku passes through the preliminaries, but meets Piccolo Jr., and the girl he promised to marry, Chi-Chi. In the finals, Goku fights with Piccolo, under the rule that he cannot use items. Eventually, Piccolo is beaten and Kami offers his position to Goku, who promptly refuses. Goku and Chi-Chi fly off to Ox-King's castle to get married.