Why does the one girl....

Good question. Singaporean actress Alien Sun is fluent in four languages, including english. Is she obviously singaporean to japanese audiences? If so, her multilingualism may simply be a quirk of her character. Yet we see Kakihara and others responding to her english as if THEY, too, understand it perfectly. What gives? Are yakuza commonly polyglot? Do singaporeans drift from one language to another? Did someone slip a gag-script to Alien Sun, and never tell her? If there is a subtext, significance, or meaning to this I am unaware of it.

That was a rather odd touch.

What do you think this is, a signature? It's a way of life!

to show that she is educated?? a cut above the other whores??