What is Showa Day like in Tokyo?
Oh god. Whatever you do, do not try to use Narita on the first day of Golden Week. The day after would probably mitigate quite a bit of the insanity, as most of the wageslaves will be leaving asap to make the most of every day of vacation. I rather suspect (perhaps incorrectly) that you might even have less company the day after rather than the day before. As someone who has lived in Japan for several years, I must confess that it strikes me as somewhat conspicuous that I can’t think of a single interesting festival I’ve ever seen on Showa day. You’ll undoubtedly be able to find something interesting to do, but I’m not sure how likely it is that it’ll be in Tokyo itself. Most of the really unique festivals I’ve been to were out in the boonies. A friend of mine just went to a firewalking festival (complete with massive bonfire, of course) that required about two hours of driving to get to. All that said, I’m not sure how accessible any of those would be if you don’t speak a bit of Japan