Is 4 weeks too long of a stay in Japan?

Hi there!
I'm new on here and would really appreciate as much advice as possible :)

I am planning to visit Japan for 4 weeks. 2 weeks in Tokyo, then then rest around Japan. Do you think that is enough time to travel around the rest of Japan, or shall I reduce the stay in Tokyo and extend the rest of the time travelling the rest of Japan?

Also, regarding accommodation. Is it possible to book rooms on the same day as I arrive? I have already sorted it out for Tokyo, and I have also made bookings for a Ryokan, as I read how hard it is to book them on the day.

Many thanks in advance

Do you think that is enough time to travel around the rest of Japan, or shall I reduce the stay in Tokyo and extend the rest of the time travelling the rest of Japan?

If you are straight travelling, then personally I'd reduce it to a week in Tokyo and then 3 weeks elsewhere. I'd also recommend budgeting a fair amount of time to explore Kansai (Kyoto, Osaka, etc.).

Also, regarding accommodation. Is it possible to book rooms on the same day as I arrive?

Yes, but risky and relatively more expensive and time consuming. I'd book at least a day ahead if possible. Very easy to do over the internet on sights such as rakuten travel.

Also, regarding accommodation. Is it possible to book rooms on the same day as I arrive?

Depends on when and where .
At Certain places and at Certain times of the year accommodations can be fully booked.

I agree with the time being spent less in Tokyo and more in Kansai.

Depending on where you are staying there may or may not be accommodations. If taking cheaper accommodations like Budget hotels or hostels, with hotel booking websites helping to compare prices such places may be fully booked on the day itself.

Remember the number of hotels are equal to the popularity of a location.

I would recommend 5 days in Tokyo
A week to 9 days in Kansai + Hiroshima
5 days for Kanazawa Takayama Tateyama Shirakawago
The rest of time for Hiroshima or Day trips from Tokyo

2 weeks is too short for Tokyo and also too short for the rest of Japan. You have to make choices depending on what interests you, we can't do it for you.

It really depends on what you like.

Some people say that 2 weeks in Tokyo is too long or not long enough.

For my personal tastes - I'd probably stay 3 or 4 days in Tokyo and then travel the rest around Japan. However - you can also use Tokyo as a base and complete day trips to Kamarura and Nikko.

If you like temples/shrines then I'd spend quite a bit of time in Kansai. However - if nature is more your thing then I'd spend some time in Chubu, Tohoku or Hokkaido.

So to help us help you - what things are of interest to you the most??

Your budget and travel speed is important too.

Intercity travel can be expensive, especially when comparing to other parts of Asia.

Are you into challenging walking trails or conquering shopping malls?

Thanks to everyone who has took their time to replied, i really appreciate it :)

Here is more details of what I am planning and what I want to see.

I am planning to visit Japan in November. I thought of travelling from Hokkaido first and then slowly travelling south of Japan for two weeks, and then spending my last two weeks in Tokyo.

I want to see a mixture of history, nature and modern life of Japan, but i mostly want to see Tokyo but I don't know whether spending two weeks in Tokyo is too much and I'm worried if I am planning on spending too much time in one place, I will be missing out on other hidden treasures within Japan.

This is why I was wondering if two weeks travelling the rest of Japan is enough.

Many thanks in advance

I forgot to mention I will be purchasing the JR pass and will be spending the first two weeks backpacking.

I hate to suggest this as it seems that your
plans are pretty firm.

However a trip to Japan would be very incomplete if you did not see Kyoto At lest for a few days. You might lessen the time in Tokyo [ which is in many ways like other big world cities] and zip to Kyoto that has the essence of Japanese culture, beauty and charm. Not to be missed.