How to book lodgings in Ozegahara?

There are lodgings inside the park, but where do I book them? I don't want to risk going there and booking on spot. Please if you could help, I would greatly appreciate it. Thanks.

Here is a list of huts with phone numbers and websites. Some have English websites:
http://homepage2.nifty.com/ma0011/oze/yado.htm

I believe that all lodgings within the park "must" be booked in advance, I believe it is to cap the number of visitors/lodgers to the park (to the extent possible) to preserve the wetlands. No shampoo, no soap, no toothpaste (as far as I remember), and please plan to arrive at the lodging by 4 pm or so. Enjoy your visit!

Thank you for your useful information. I'm going at the end of the month so I hope it's not quite peaked season yet and that there are still some vacancies. Thanks again!