Questions Concerning Staying in Japan

I am going to Japan in the off-season (In October, that is the off-season right?)in a year. I plan on traveling to Nagoya, Tokyo, and the Kiso Valley (Tsumago, and the other town). Do japanese hotels, and Ryokans accept people who do not make reservations? I kinda want to travel around japan and do things as I do them (like stay at a inn the night/day I arrive there. Do you think it would be relatively easy to do this if it is possible?

We have been to Japan twice now. The first was pre-internet and we just back- packed around and used travel guides as references and rang each day to book accommodation. While this meant we could be flexible it was very,very time consuming, as very few places spoke much English. We got al lot of hang ups because they couln't understand us. We chose to try to ring up before just arriving on the door step to enquire. Otherwise alot of time can be chewed up trapsing around at the end of a long day looking for somewhere to stay then having to go out again often to find somewhere to eat. Remembering that in Japan restaurants aren't always as obvious to Westerners as we are used to-Look for the fabric hanging down from doorways for great little bars that serve inexpensive meals.

The second time we returned to Japan in the last few months, we did a lot of homework before we left to maximise our 3 weeks there. We booked everything over the net before we left and found it to be a Godsend. There is enough cultural difference and amazing experiences to be had without the drama of constantly looking for accommodation in a non English speaking( and writing) country.Outside the big cities there is still very little in English. You can get by okay but we found that there was enough to cope with without worrying every day about where we were going to stay. This way we knew exactly where we were staying, how much it would cost (usually cheaper on the net anyway)and we could print off maps of how to get to each ryokan before we left. Even with the maps it we found it rather challenging at times.
So I can see where you are coming from. In an ideal situation it is great to be flexible but just keep in mind that it does use up a lot of time. All the best. We absolutely loved our time there and are already planning to return!

Try these websites-

For rail timetables-http://www.japanrail.com/JR_hyperdia.html

For accommodation-
http://www.itcj.jp/
http://www.japaneseguesthouses.com/index.htm

October is a good time for staying in Japan. University begins in the second half of October, so it is less full than the first half. I think you had better reserve your accomodation in advance, especially if you go to Kiso Valley or anywhere else in the country side. Most Japanese are neither used to deal with foreigners nor find it easy to speak a foreign language. Therefore, you might be refused accomodation if you show up at a hotel without reservation. Even if you can speak Japanese, you might have a difficult time explaining your name on the phone.

If you are willing to be flexible about the type of accommodation, you can probably find a place everywhere you go. Most towns that have any tourist attractions, also have a tourist information office. They can be very helpful in booking same-day accommodation but often these offices close at five or so. Also, off the beaten track a bit, you are taking your chances about whether you can find an english-speaker.
If you arrive too late in the day the ryokan most likely can't feed you dinner, though they may charge you full rate anyway.
Business hotels and love hotels are also an option.
I would compromise a bit, I think - book at least some of your nights, so you know where you're going and are assured a welcome.
I was in Magome, a small though touristic town, in winter, as it was getting dark and honestly I had a hard telling which buildings were ryokans and which were even open. Not reserving accommodation means you should plan on being in the area you want to stay, early.

My last trip to Japan was in October and November. I would suggest making reservations in advance, here is an inn group where you will have a good chance of getting English speaking help. Many of the lodgings are traditional ryokan.

http://www.jpinn.com/

Many places will take walk ins with no reservation but you might also find the only rooms left are more expensive than you want to pay. Places in Tokyo and Nagoya can fill up fast but there is always a capsule hotel or a chain like Washington Hotels that will more than likely have vacancies.
The weather, by the way, was quite lovely in the fall (most of the time) but don't forget to bring your umbrella.