Definitely a cause for celebration, but since Zormau already started the trend of comparing Japan to our countries of residence, I might as well add my two cents.
The Japanese are once again ahead of Montenegro. Here, we just legalized civil unions last year, so we probably can't look forward to legalizing same-sex marriage for at least a decade or so. (After which, I assume we'll follow in the trend of western countries by having trans rights specifically become the most contentious civil rights conflict.)