What is open on a National Holiday

We arrive in Tokyo on the evening of the 22nd. The day after we arrive will be a National Holiday (23 September). Will many things be closed that day and will public transportation be affected? Any suggestions on what to do on that day would be appreciated.

Virtually all tourist attractions and shops and restaurants will be open. Among the few exceptions is Tsukiji Market, which will be closed.

As mentioned, every touristical excitement will be opened for all the people who are enjoying their day off (shopping, dining, sightseeing etc.). However, because of this, you will find the city very crowded including public transportation. But trains are hardly delayed.

Thank you for your replies. I suppose seeing crowds of people is part of Tokyo itself. I have always been fascinated by those pictures of the white gloved handlers helping push people into the trains. It is something I should probably try once in my life :). Thanks also for letting me know about the fish market being closed that day.

To see white gloved station staff push passengers into trains, you will have to ride trains on a regular weekday morning.