Momo will convert your Japanese traffic best, here's their English page:
http://MoMoSystems.com/e/index.html Japanese surfers are very selective and have to be targeted, unless they see prepubescent girls being raped they won't join.
My program Chinatown-Girls.com will convert more general Asian traffic really well and we offer our partners tons exclusive Asian content to promote the site with (shot right here in Chinatown NYC). We don't have a webmaster referral program though so might not be the best bet.
http://Chinatown-Girls.com/webmasters/index.html