You dont unless you know them personally and nobody who is friends with anyone in the JAV industry as a star will give you their private personal information.
You can... oh say... PAY us to introduce you.... but there's no way in hell I or anyone else would simply give you someone's phone number, email or even Facebook link.
There's no point unless you know Japanese anyways.
Even if you get their twitter or somehow got a hold of their contact deatils, I doubt they'll care enough to find a manager/translator to communicate with you.
here the main issue with your post. since they are seen world wide. also the fact that most or majority them do not know English. you also got the point some else said too. where or when will they have time to replay to every one tweet or Facebook message or blog page. also got the fact majority or most of them want to life private life out side work too. that why they have blog for update so there close friends or coworkers can follow them on what they been doing since there close people to person. so odds fan getting to contact one might be hard one. yes they get mail and letter from there fans but odds of them being able to read or replay to all them is like one drop of water in huge pond.