Note that the copyright is not about the source country of the work, but where do make/distribute the copy. Do you live in Japan, or are you interested in Japanese works? (Or both, possibly.)
That's NEAT! I live in Japan myself, and I am a passionate Japanese learner (and used to be a teacher too) of multiple decades. Besides, I'm interested in natural language processing and language related technology, and used to study second language acquisition research back in the university. If you ever take part into any tech / language events or meetups, it would be nice to hang out and hear about the development of that app.
