I mean, lower courts don't mean a lot in the grand scheme of things, for better or worse. It seems clear that the lower courts are trying to legislate from the bench in service of a moral good. The constitution is extremely unambiguous about this:

  第二十四条

  婚姻は、両性の合意のみに基いて成立し、夫婦が同等の権利を有することを基本として、相互の協力により、維持されなければならない。

With "両性" unambiguously meaning "both sexes" and "夫婦" unambiguously meaning "husband and wife".