In case anyone is curious why Emma speaking Japanese is such a big deal . . . .
Spoiler!
The kingdom and Imperial Japan are in the middle of a trade negotiation in which both sides wants to make this work. But due to language barriers it's been a problem. It's gotten to a point that the kingdom thinks there is some weird organ that makes it impossible for them to speak/learn Japanese. Thus why Emma speaking the language is such a huge deal.
