I am not a Japanese and only knows about Japan from manga, so please cmiiw, but in Japan, not using honorific means you are very very close.He already calls her Chihiro-san, so just taking away the san is something very embarrassing, it's difficult to understand this 100% because he already calls her by name, she should be used to it. I always wonder if this actually happens in real life.
You need to eat more sushiThis is one of those Japanese things I'll never truly understand.