I have been thinking of making a language learning game of my own as well, but I have no idea how to start without making it look too much like something else already available. But it seems like you have nailed alot of the aspects. Though since I am a native Chinese speaker who also happened to have learnt a little Japanese on the side, the chaos was unfortunately lost on me. But hopefully everyone else finds it entertaining.
However, I feel the graphics assets were kind of inconsisent with a mash of pixel art in the background, an animated sprite for the player and a Kanji character for the guide. Maybe you could do a sort of joke by making the player a Latin character or Katakana to imply that they are uninitiated?