iriver's products are available at major electronic stores in Japan such as Bic Camera, Yamada denki, etc. You can see a list of shops (in Japanese) which sell iriver products:
http://www.iriver.co.jp/sales/byregion/
The problem will be relase date, which we don't know at present. I don't think international version of H10 is available in Japan. But as far as I tried, we can choose other languages when installing iriver plus.