Public Restrooms in Tokyo?
 

Are they plentiful? I have a weak bladder.

Any train station or shopping mall has public toilets. No problem...

Most big-name convenience stores now have restrooms as well. You don't have to buy anything to use the restrooms, either. If you're 18 or older, you can go into a pachinko parlor just to use the restroom. The more places to count on, the better...