We are working on an Android/iOS Japanese crossword app built for relaxing, centered on word lists that work for you.
No screenshots yet, but we are looking for early access testers! We should have something to test by the middle of September.
If you are interested in testing, please reply with either "iOS" or "Android" as your message (nothing else, please).
Also, please make sure your email address in renshuu is up to date, as that is what will be used to add you to the early access list when it becomes available.