Itinerary advice for 23 day trip

Hi,

I am spending 3 weeks (23 days) traveling around Japan (setting off on 22nd July). I absolutely can't wait as I have never been to Japan but have heard wonderful stories about it and would love to experience it firsthand.

My itinerary at present is:

4 nights in Tokyo
1 night in Nikko
3 nights in Kyoto (with a day trip to Nara)
2 nights in Hiroshima (with a day trip to Miyajima Island)
2 nights in Nagasaki
3 nights in Miyazaki
1 night in Beppu
3 nights in Osaka (with a day trip to Himeji)
3 nights in Tokyo
Then (sadly) flying home to sunny England.

My main question is about my time spent on the southern island (Kyushu). How long is it likely to take us to get from Hiroshima to Nagasaki? And then from Nagasaki to Miyazaki. Although I will be happy to spend some time on trains I don't want that to be the only thing we do when we're there and I am worried that I am cramming too much in by visiting both Nagasaki and Miyazaki.

Any advice would be greatly appreciated.

Thank you in advance,

Catherine

How long is it likely to take us to get from Hiroshima to Nagasaki?

3.5 hours

And then from Nagasaki to Miyazaki.

Assuming you refer to Miyazaki City, 6-7 hours.

Here is a very useful tool for looking up train routes and travel duration:
http://www.jorudan.co.jp/english/norikae/

May I ask: why Miyazaki? And why as many as 3 nights?