Kamesennin Mutenroushi also known as Master Roshi was once one of the greatest fighters in the world. He won a tournament in Budokai. He was the strongest fighter 50 years ago. He is a turtle on his own island and his house is name Kame House. His only friends there is the turtle. Now he is just a dirty old man.
Master Roshi was the one who trained Gokou for the first time. Gokou first saw Master Roshi shoot a KameHameHa when he was shooting a navy of boats away from his island, where he lives. Gokou easily shot one too and Master Roshi was amazed because it took him 50 years to master it. Master Roshi knew that Gokou had a lot of power and had to train him. Master Roshi taught Gokou a lot of things. He taught him to never give up and that there's always room for improvement. He gave Gokou a present when Gokou was young. It was Nimbus, a very fast cloud that can only be ridden if they have a pure heart.
Other people that he taught are Klilyn, Tienshiha, and Yamcha. He made his own style of martial arts known as the Kamesennin style. His logo is shown on the clothes of Gokou, Klilyn, Yamcha, and Chaozu. He was a great teacher.
Now that he's grown up and old, he is not that strong anymore. His power level is only 139. Every once in a while he'll get angry and get really big muscles. Then he'll do his own move, KameHameHa. Now that he's old they all (especially Bulma) make fun of him. When they see him power up they think it is a joke and forget that he was once the strongest on earth. They just call him "a dirty old man"