Wow! I feel like this could be a good way to learn Japanese words. Sometimes I got stuck for a little while, and eventually figured things out, but maybe having a hint button would be great if I were to get stuck for a long time.
Another small comment is to have some way to highlight (or arrows pointing to) places where I haven't completed yet. For example, if I'm at 16/17, sometimes it takes a while to find where the last missing question is.
I really loved the intro clips of the plane and train. I wasn't sure if it was part of the loading screen, but it helped to make me feel like I was entering Japan.