It would take infinitely long time. Japan don't give a fuck about what westerners think as morally correct or wrong. Google recent Tate no Yushaa outbreak and how Japanese answered. They don't give a fuck. Also there is ZERO amorality in any form of hentai because real people don't participate...
As long as fact of translating, downloading and playing isn't pursued legally it doesn't really matter. Most of anime/hentai translated unofficially anyway. So how could they end Japanese culture? Ten years ago basically ALL Japanese culture stuff was unofficial almost completely and still it...
