From the manga Saiyuki. He's based on Sun Wukong, the Monkey King. He's been in the Nexus far too long and is at this point an AU.
Goku is 5'4" and whip-chord thin. He appears as though he's about 16, but he spent 500 years alone trapped in a cave with out food or water, and he did not age, although his body seems to be trying to make up for the lack of food, and now he's always hungry.
He tends to come across as a bit daft, but that's because he sees the world in a completely different way, and tends to be single minded. This is also because Goku is not human, despite his appearence.
If your character is sensitive to such things, they may get a sense of enormous power, and age. Son Goku's true form is called Seiten Taisei, the Great Sage Equal to Heaven.He was born from a rock where the Earth's aura gathered, and he is able to harness the planet's own power to use. When he is on his world he is effectively immortal,