North Kaio (北の界王, Kita no Kaiō?) (English dubs: King Kai, North Kai) is the Kaio of the quadrant of the galaxy where the planets Earth and Namek reside. In the English manga, he is also known as Kaiô-sama or Lord of the Worlds. Claiming himself to be very humorous; he will only teach his subordinates if they laugh at his non-comedic jokes (really bad puns in the original Japanese). He can only train those who can reach the end of Snakeway. He trained Goku, who succeeded in doing so and taught him very powerful techniques that have been essential to many of his battles: including the Genki Dama (Spirit Bomb in English dubs) and the Kaio Ken. (Source: Wikipedia)