Sasuke is the robot dressed in green.
Not human, but he's a cute little robot ninja created by the Wise Old Man.

Goemon and Sasuke fought each other when they first met, but now they are friends.

Sasuke seems to have the power to actually change his gender (don’t ask). Also, Sasuke has a switch which makes him either incredibly nice or a total villain (Sasuke is totally weak as a villain though)

Sasuke adores having a hot bath and drinking green tea.