Who is Mochida from The Master Puppeteer and what is their importance?

Mochida is the left-handed operator at the theater and is in charge of the apprentices. He oversees their practices and tells them when they have made errors. He is much kinder than Yoshida and will not beat them when they make mistakes. However, he also does not explain what they have done wrong, which Jiro finds frustrating as it makes it harder for him to know how to correct the mistake. Mochida seems to genuinely care about the boys, and even lets Jiro off work to go see his mother. Mochida is high in the social ladder of the theater, but is not Yoshida's equal and admits to finding the master puppeteer frightening.