@slothrop I wrote up suggestions for a friend a while back (updated the visitor sim card section this year after my last trip). I didn’t include budget aspects so much though (Japan is expensive but you can get by.)
I recommend!
Japan is splendid, elegant, safe, peculiar, and the Japanese are nice.
https://blog.koalie.net/2015/03/07/vacationing-tips-and-suggestions-for-japan/