Many Dragon Ball Z fans are well-acquainted with the adult adventures of Goku and the Z Fighters as they defended Earth from escalating threats. However, the original Dragon Ball anime series is more of an overlooked story in Akira Toriyama's landmark manga/anime franchise.
Following the adventures of Goku as a young boy, the 153-episode series adapted the 194 chapters of Toriyama's manga series. It culminated in a marriage for its protagonist as Goku reached adulthood and featured a showdown for the fate of Earth against Piccolo, Jr. -- the son of one of the story's most prominent antagonists, the deadly Demon King Piccolo. By the time the final battle concluded, Goku was indisputably the strongest man on the planet at that time, claiming his martial arts destiny.
The original Dragon Ball revolved around the World Martial Arts Tournament, held every three years to determine the greatest fighter in the world. Goku entered his first tournament, the 21st World Martial Arts Tournament, at the age of twelve alongside his best friend Krillin, Yamcha and a disguised Master Roshi. Roshi would eventually emerge triumphant over his star pupil after a narrow fight. Afterward, Goku would spend the next three years training and preventing the Red Ribbon Army from using the Dragon Balls to conquer the world. The 22nd World Martial Arts had Goku take on his new rival Tien Shinhan, just barely losing out in the final round due to his opponent's height.
The 23rd World Martial Arts Tournament brought in many of the familiar faces Goku had encountered over his past adventures, including Krillin, Yamcha, Tien, Chi-Chi and Mercenary Tao. Joining the participants were two surprise fighters: an unassuming human man named Hero and Piccolo. Piccolo was the near-identical son of King Piccolo, who nearly conquered the Earth and bested the Z Fighters, with Goku barely able to defeat him. Piccolo entered the tournament to avenge his father before fulfilling his father's dream of subjugating humanity. Hero was revealed to be Piccolo's opposite and the Guardian of the Earth, Kami, who secretly entered the tournament in his human disguise to defeat his counterpart.
As Goku and Piccolo progressed towards the final round, the Z Fighters revealed how far they had come since the previous tournament three years prior. Krillin mastered the ability to fly while Chi-Chi revealed her past promise to marry Goku, with the young man accepting (though privately not understanding what marriage meant). While Goku and Tien fought evenly at the past tournament, Goku demonstrated how far he had surpassed his old rival while Tien rejected his past evil ways for good. The tournament's final round had Goku and Piccolo face-off. Goku would then narrowly defeat his opponent and win the competition, marrying Chi-Chi soon after that while Piccolo vowed revenge.
Goku's ascent to adulthood culminated in finally becoming the most powerful martial artist in the world and fulfilling the marriage promise he unwittingly made as a boy to Chi-Chi. With past rivals like Tao, Tien and Piccolo all resurfacing, Goku ultimately triumphed at the end of the original series, after two near-attempts to win the World Martial Arts Tournament.
Between Dragon Ball and DBZ, there would be a five-year time jump that saw Goku and Chi-Chi more firmly settled into domestic life, now with a young son of their own in Gohan. The overarching story itself took a much darker tone and science fiction orientation, a departure from the more light-hearted Dragon Ball and its fantasy sensibilities.