Also, make sure you have a washcloth/small towel in your bag and a pack of Kleenex for public restrooms - generally no paper products available for stalls or sinks.
This is good advice! You will notice the locals carry this with them everywhere, especially for after washing hands. The large department stores in Tokyo do have toilet tissue in my experience.
You will notice how quiet it is....and that is a good mirror of how people dress and act. The women are stunningly put together and very elegant!! Practice and learn some basics. Hello/Goodbye, Thank You and how to hand people a business card (and receive one) along with the slight bow - that is very important in Japan.
I hope you have a good trip - I have been twice and absolutely love Japan.