Sonny’s role in the movie was alright as the Hattori Hanzo. However that character appeared in various of Samurai films as a famous Samurai and or Ninja. Dunno why but I think that the Sonny wanted to portray him like a sensei to Uma in Kill Bill Vol. 1.

He was playing a direct decendent of the Hatori Hanzo from the 70’s show he did. He had put up his swords & said he’d never make another. In the movie the only reason he made a sword for Uma was because he had trained Bill & felt responsible!