Sasuke Sarutobi

A "ninja monkey" bred by Dabi-no-ji. His true identity is that of Sasuke Sarutobi, one of the Sanada Ten Braves. He was transformed by the gramary of Yasha because he learned too much about Yasha's plans. Although he is called a "genius ninja", his skills are only equal to that of Ninja-Taro.

(Source: Wikipedia)