They're not going to win. Japan is still a socially conservative country and will not fall for the political movements that are taking place in the west.
https://en.wikipedia.org/wiki/Recognition_of_same-sex_unions_in_Japan
Is that why most polls show support for marriage equality in Japan? Homophobia as it exists in the west is also very rare in Japan, by the way.
As much as it pains you, I’m sure, gay people are here, we’re here to stay, and we exist all around the world.
In every nation and on every continent.
I imagine the fact that Japan is dominated by the LDP (which is still generally conservative) is the reason why same sex marriage has never been legalized?
Probably that plus I guess cultural differences regarding huge influence by older people (more conservative)