I heard from one of my friends working at Yahoo! that Yahoo!Japan does not review any commercial sites from free submission. You need to subscribe paid review when you are gointg to submit commercial sites.
Yahoo Japan does not include any new commercial sites for free. I have been submitting to Yahoo Japan since it opened and have found that for the past 6 months or so there have been few to no free submissions accepted in any form.
We have tried submissions as well as asked them directly and it is no go. If you want to be in you have to pay.
The other problem is that if you do not have sufficient Japanese content they will reject the paid listing. You then have to go through the appeal process once you have added "sufficient" Japanese content.