Trains in Tokyo are notoriously busy (this video gives you a good idea), but for the likes of the elderly and pregnant, there’s one saving grace. The silver seat. Situated near the doors, it allows easy access in and out of the carriage, and train manner dictates that these seats be given up to those that need them.
Now thanks to a kind e-mail from Andrew over at Grannybuttons, I have a picture of a silver seat and its sign. It should be pointed out that it may have been altered slightly.