From your handle I will assume you are a male.

My experiences as a female in these areas are irrelevant to those you can expect.

With the exceptions of a couple of unisex facilities I have had the misfortune of needing to use (having visited Tokyo whilst pregnant, my familiarity with public toilets is considerable), the Ladies' services are all impeccable. One only needs to take a supply of toilet paper/tissues. I would also suggest portable soap or soap leaves as neither soap nor paper are supplied at the majority of station rest rooms.