Hello everyone, I'm Momozuki!
From Dragon Ball to Dragon Ball Z, to Dragon Ball GT or Dragon Ball Super, we have witnessed Goku's journey of repeatedly defeating strong enemies, constantly surpassing limits, and finally growing into the top powerhouse in the universe. This road of the strong is full of hardships and obstacles, there is no end, and if you slacken off, you will end up with a ruined family.
Fortunately, Goku is very lucky, on the way to defeating the strong enemy, there are not only comrades in arms who are friends of life and death, but also four mentors who guide him to the strongest way, without the teaching of the masters, there is no future Sun Wukong.

1. Turtle Immortals
An old man with a squint, but an extremely responsible heart for teaching. He used strict and life-like teaching methods, such as ploughing the ground by hand, delivering milk irregularly, swimming with sharks, etc., to subtly lay a solid foundation for Goku and Kling.
The Turtle Immortal also transformed into a dragon, letting Goku know that there are people outside the heavens, laying for him the heart of a strong person who constantly cultivates and constantly transcends the limit.
2. God
In order to thank Goku for defeating the Great Demon King of Bik, and to deal with Bik's successor three years later, the god personally guided Goku's three-year practice in the temple.
This is Goku's way of learning the use of 'qi' in a systematic way, not only that, the god uses the special device of the temple to make Goku fight with various time and space strongmen, so that Goku can master the use of qi.
This quickly opened up the gap between Goku and Tianjin Rice and others, you know, the Saiyans attacked Tianjin Rice and other people to accept the guidance of the gods, and at this time Goku had been ahead of their nearly ten years of skill.
3. King of the North
After the Saiyans attacked, Goku practiced in the Northern Realm King Star for half a year (half a year to run the Snake Island), and learned the secret of the King of the North Realm: the King of the Realm Fist and the Yuan Qi Bomb, these two moves can be said to be the absolute magic weapon to reverse Qiankun. In the future, Goku used these two moves many times to turn defeat into victory, if there were no these two moves, the earth would have exploded long ago.
Compared with the Turtle Immortals and the Late Divine Decorations, although the Northern King taught Goku for a short time, his influence was great. Whether it is the Sharu chapter or the Demon Buu chapter, the King of the Northern Realm has played a crucial role. Without the Northern Realm King Star, Goku could not think of a good place to transfer the explosion of Saru, and the earth would explode; without the Northern Realm King's teleportation technique, Goku would not be able to gather the super large Yuan Qi bomb, and the earth would still explode.
4. Weiss
As the master and steward of the Seventh Universe Destroyer, Weiss is highly respected and powerful, but this does not hinder his appreciation of Goku and Vegeta. In fact, without the cultivation of the Destruction Star, Goku would not be able to practice the Self-Reliance Extreme Technique, and the Cosmic Fighting Conference would have been killed by Ji Lian, and the Seventh Universe would probably be erased.
Of the four masters, only Gui Immortal and Goku have the title of master and apprentice, and the other three do not have the name of master, but perform the position of master. They can be said to be noble people on the path of Goku's strong, but they can't be sought. Of course, as long as the story of Dragon Ball continues to be serialized, there will be Goku's master in the future.
(Picture from the Internet, invasion and deletion)