Comments on final itinerary please.

Seishun 18 pass isn't valid on express trains either, just local and rapid., well it wasn't when I used one last.
According to JR East page
"unlimited rides on local and rapid trains (excluding reserved seats) within the designated open seating zone on the following transportation services:
All JR company lines (including Bus Rapid Transit) throughout Japan – JR Hokkaido, JR East, JR Central, JR West, JR Shikoku and JR Kyushu
The JR West Miyajima Ferry
Even in combination with a Super (Limited) Express Seat or other special ticket, the Seishun 18 cannot be used for travel on Shinkansens, limited express trains, express trains or sleeper cars."
Osaka to Matsumoto by local/rapid is around 400 minutes according to hyperdia

I don't know where to start! First off, as above, the Seishun 18 tickets are only valid on regular trains. Essentially, what JR calls local trains and express trains. Limited Express trains and the Shinkansen are not covered by the Seishun 18. It takes a long time to get anywhere using the Seishun 18.

Next: Koyasan to Kyoto in a day, via Nara, is silly. Getting from Koyasan to Nara is a little convoluted. You might want to look into heading directly to Koyasan from the airport? Give yourself a full day there, and then leave in the late afternoon or evening, ending up in Kyoto or Osaka. If you want to go to Nara, visit as a day-trip from Kyoto.

Matsumoto is on the way between Takayama and Tokyo! Your current plan makes no sense. If you want to visit Takayama and Matsumoto, then head from Hiroshima/Osaka to Takayama, and then visit Matsumoto after, on your way to Tokyo. Hiroshima-Himeji-Takayama in one day is crazy, and you'll only make it using expensive trains.

If you want to save money, don't move around so much (ie. drop Hiroshima), and don't visit expensive places, like Shirakawa-go. I think you need to be more realistic about travel times, and I also think you need to realize that it's not necessary to buy a pass for everything. Many of the passes will not save you money.

Thank you for your advice. I am a novice when it comes to trains so will forget the use of the Seishun pass. I will revisit the itinerary and put Matsumoto after Takayama. I will also investigate the fares without the passes. Hyperdia is not working for me at the moment so i am hoping to get that figured out tonight so that I can do cost comparisons. I am finding getting the right balance between seeing everything we want to see, and not being too busy a bit of a challenge.

If you're fixed on the places you want to visit, then to maximize your time, here's what I would do:

Head straight to Koyasan from the airport. Spend the next day there, and leave in the late afternoon/evening. Depending on how you feel, either head to Osaka for the night (you can take it the nightlife of Namba), or travel on all the way to Himeji. Either way, visit Himeji castle the next morning (getting up early, so you're there when it opens), and then head to Hiroshima in the early afternoon. You should have time to see the main Atomic museum. The next day, go to Miyajima, and then jump on a train to Kyoto after dark (it gets dark early in December!). Spend your time in Kyoto. Travel from Kyoto to Takayama, which isn't such a crazy day. If you decided you liked Himeji a lot, stop off in Hikone on the way, which is another lovely castle. From Takayama to Matsumoto, and then to Tokyo.

Hi
Thankyou...that makes a lot of sense. We don't arrive till around 1230pm so I was a little concerned about going straight to Koyasan as I believe that the cablecar will be out of order as they are replacing the car. This means a slightly longer bus trip. I will work out times tonight to see if we can make it work but I thought Osaka would be a safer first night. If we arrived earlier in the day your plan would be perfect and it still might be best. I really see the merit in your suggestion. Could I please ask how you would split Kyoto/Tokyo time. We would like to see Hakone and maybe Kamakura from Tokyo, but we like to sightsee and walk more than shop. If we only spend the one night in Hiroshima it does mean we can add a night to either Kyoto or Tokyo. I am thinking Kyoto at this stage. Many friends tell me it is their favourite city in the word. I also wonder if three nights is too much in Takayama but we had hoped to do the Ropeway and maybe Shirakawago. Takayama seems to get mixed reviews with some people loving it and others finding it overrated.

Transport to Koyasan has been crazy all year, with many issues. I don't know what the situation is currently like, or what the details are with the cable car. If the cable car's not running, then you'd either have to hike up, or take a bus, probably from Hashimoto. You'd be able to make it there from Kansai Airport that evening, but if you're meant to end up at a temple by a certain time for dinner, then yes, it might be risky. If you spent the night in Osaka, you could go to Koyasan earlier the next day, giving you plenty of time to do Koyasan-Himeji the day after, say.

Both Kyoto and Tokyo are fascinating cities, with way more to do in them than you will be able to fit in. Kyoto is an ancient city, with a plethora of historical, cultural, and architectural sights and places of interest. Tokyo is the heart of the biggest city in the world, and the center of Japan for the last 400 years. You can't go wrong spending time in either.

I really like Kamakura. It's a great day-trip from Tokyo. Lots of interesting sights to see, and some great hiking. If the weather's good, you can see Mt. Fuji from Kamakura. Go early in the morning - Kamakura fills up with day-trippers during the day.

I personally don't like Takayama very much. It's too touristy for my tastes. Shirakawa-go is incredibly touristy these days, though I haven't been in winter. I've also never been to the Shinhotaka Ropeway. I wouldn't recommend 3 nights in Takayama personally, but as you say, some people do like the place a lot.

Thankyou so much for your time. I think that we would be best to overnight in Osaka and then head up early to Koyasan the next day (if we were arriving earlier in the day I would definitely go straight there). I'm not sure how long customs will take and if we have a flight delay I will be a wreck if I am worried about getting to a temple on time. I am really looking forward to Okoiun and Koyasan and don't want to be stressed getting there after a long flight. I really wanted to see the area around the Japanese Alps hence Takayama but am now wondering if we should spend out time elsewhere. My children would love to see snow but I don't think it is guaranteed in mid December anyway. We are busy travellers and like to see things most of the time but I don't want to come home exhausted either. We just want to have a wonderful trip. There is so much to see in Japan that I am sure we will be back but I am trying to make the most of the days we have.

That probably makes a lot of sense for you to spend the first night in Osaka then. Customs is usually pretty quick at Kansai Airport, but delays are always possible. Public transport is now running normally at the airport, after a disasterous typhoon this summer.

Osaka the first night should be fine for you..stay somewhere near Namba so you can head towards Koya early morning.

Apart from that...Takayama before Matsumoto certainly makes sense with that itinerary and route.

Kyoto vs Tokyo..as Giora says,you can't really go wrong with either.On a first trip I'd give them equal weight,on subsequent trips you will decide if you prefer the ancient side of Japan,or the modern ;-)