homestays

is it very difficult to find homestays in japan? is there a way to organise it from outside japan? I'll be spending a one year working holliday in Japan

Try the following website. You might be able to find something about homestay in Japan.
www.afs.or.jp/jpn_ja/visiting

JTB, the largest travel agency in Japan, has announced that it will start homestay business next March. As they are still at the stage of collecting host families, no details are available. (and the webpage itself is still Japanese only) I suggest you to check the page from time to time.
http://www.jtbbwt.com/homestay/

try google "homestay japan" .. anyway here's some website you can check, in english

http://www.homestayweb.com/jphome.html
http://www.eiljapan.org/index_e.html