Goku is the hawt bishie from Gensou Maden Saiyuki that is like 500 years old but magically looks more around 18. He was placed away in a mountain with cage like formations for bars that made him really tweaked out. He had a pet bird that unfortunately died outside of his reach.
He also had no food and could only wait for Sanzo
to come rescue him. Sanzo obviously did save him only because he couldn't tolerate Goku's 'crying out to him' no longer. So the two left and Sanzo became a 'babysitter' and Goku became one of Sanzo's followers.
His token sayings are "Harahetta!" (I'm hungry) and "Sanzo" (just take a guess). He also likes to fight with Gojyo and is sort of taken care of by Hakkai as well. The best thing about Goku is that he can kick major ass, namely being yokai or Kougaji. The only one that really gets to him is Homura but that's because Homura has some 'Mad War Prince Power' and some sexual induendo.
Lastly, Goku is based off the Monkey King from the Saiyuki Chinese legend just like the Goku from DBZ.
I <3 Goku long time.