God dammit japan! When will you finaly realize that you don't need two genders for a working, sexy relationship!
I was gonna say that, much to surprise us by being the birthplace of yuri and yaoi, Japan is a country that not long ago was still living in the Middle Ages where suicide was the most normal thing in the world... but as I wrote it, I remembered that there are countries that carry much more time in "modern times" and yet homosexuals are getting into prison and even condemning to death just for being gays so... it could be worse. xD
Personally, I think it will be a matter of time. Apparently less flexible countries (like, and surprisingly, Spain) have give up with that crusade, accepting and regulating it so I think that at some point Japan will eventually do the same and legalize gay marriage.
And with that, culturally acceptance and seen it as "normal" is a matter of time.