I did a search on it and haven't seen the same question. I've seen it for straight marriages but gay marriages are held to a different standard so I wanted to see how valid it would be.
Right now, gay marriages ... even if legal where they took place ... are NOT accepted in the US ... at present.
But, if we keep our current President and change the make-up of the Congress ... things may change.
Here is an example of the struggles people are experiencing: http://www.nytimes.com/2011/05/07/us/politics/07marriage.html?_r=1
Yeah, that's where our question lays. Japan will recognize a gay marriage if it was performed in a place where it's legal. But what we're wondering if it's enough for them that it's legal in the state that it took place, or if it has to be accepted by the entire country.
Ok, maybe I'm not understanding your question. This isn't a question of US law at all.
This is a question of Japanese law ... I am sorry for the confusion.
Talk to someone at the Japanese Consul or Embassy.