Ushi (ウシ, Ushi) was an Anbu member of Konohagakure who served under the Second Hokage.
He was one of the Anbu ordered to watch the Uchiha clan to keep them from rebelling again and he did so vigilantly.
Ushi wore a black Anbu cloak and a white Anbu mask over his face with a big triangular purple mark on the mask's forehead area.
As an Anbu, he was one of Konohagakure's strongest shinobi. The fact that he was tasked with the very important and difficult mission to observe the Uchiha clan furthermore implies that he was very powerful.
- "Ushi" means "cow". It is likely not his real name, but a codename.