I found this website very helpful. I just came back from a trip to Japan planned by myself with the info and link provided by the backpacking site, and it was very successful.

However, I have one tip for future backpackers. All Youth Hotels (the Japanese insist that we don't say the word hostel) in Japan don't share their kitchen, nor their fridge with backpackers; don't buy any uncooked food when travelling in Japan. All hotel operators provide breakfast and dinner with cost!