I introduce the sites offer commercial banners. LinkShare
This is LinkShare. You can post commercial easily. Even if you aren't in Japan, having an account in Japan is OK! Moreover, you can register in English!
This is A8NET.This site is only japanese.But if you are able to read japanese,please try this to get income.You can post commercial banners easily.To do it, you have to register.
You can become an advertiser,too.
I think this site is the easiest way to post commercail banner on your web page.
