I have two passports, one Hong Kong and one US. I have always used the Hong Kong one to enter Japan, but it is about to expire. Can I use my US passport to enter Japan this time, or do I always have to use the same one?
I have two passports and go to Japan a few times a year. I use whichever one I have on hand (as I travel a lot, I rotate between both) and was never asked about the other.
There are countries that insist on using the same passport (Malaysia comes to mind), but Japan isn't one of them.