Yeahhh . . . how often does the governing party ever change in Japan again?
I like how the answer is "basically never" and yet this raises far less eyebrows than it should.
That shouldn't raise any eyebrows, really. For a number of reasons.
• It was 12 years ago, which is pretty fairly average for a parliamentary democracy. In comparison, Germany's CDU was in power from 2005 to 2021, and also had two other stretches of 16 and 20 years before that. The US would also have similar numbers despite not being parliamentary if it weren't for the wonkiness of an electoral system that gives land more power than people; one party has won every popular vote since 1994, excepting 2004 which came with a very large asterisk attached.
• Stability is a highly desirable trait. A nation reversing course every four years to do the exact opposite of what it was previously doing not only fails to lead to meaningful progress, but creates a massive amount of doubt and uncertainty. Situations where parliamentary democracies are changing governments every four years or less are not generally indicative of a good thing.
• The design of a parliamentary democracy heavily mitigates the power of the leading party anyways. It is extremely rare for one party to ever have majority representation, meaning it relies on a coalition with other parties to maintain power. Even if one party remains the leader, the actual coalition in power often shifts composition between elections, and either way the leading party must compromise with its coalition partners because without their support it ceases to have power.
The main problem regarding gay marriage in Japan is that the constitution is not ambiguous. It very explicitly defines marriage as between man and woman. Ironically, despite Americans now berating Japan's backwardness, it was the US that imposed that into Japan's post-war constitution. Anyways, public support for gay marriage is high but the bar for enacting constitutional change is higher than passing a normal law so the status quo will take a while to overcome.