Here's an alternative if you want to try some actual Japanese-language signup programs. Dreamcash seems to have a wide variety of choices, from per-click (but with ridiculous conversion ratio of 1:500 or better!) to per-signup and partnership programs. And they have Japanese-language banners and Japanese-language sites (as well as an English language webmaster site)
http://www.dreamcash.com/REFRQMM7D/
Hope this helps!