public holiday travel

I will be travelling to Osaka from Tokyo on the 9th of January by shinkansen. I have been to Japan 2 times before but never been there during a public holiday. I understand that the 9th of January is a public holiday, I will have my JR Pass, but will i need to book a seat on the shinkansen? I know that the trains are busy on public holidays. I will be travelling early morning, will that make a difference with beating the crowds?

The situation is unlikely to be extreme. And the "return rush" at the end of the 3-day weekend is mostly taking place in the afternoon of the 9th in direction of the big cities (especially Tokyo).

You should be able to make seat reservations for many trains the day before or even on the day itself. If you can do it even earlier in advance, even better. Of course, it also depends on what train in what direction you are planning on taking.

If you fail making seat reservations, note that most trains also have non-reserved seating that you can use without seat reservations. In the worst case, you may have to stand.