They wouldn't be able to adopt a child together in Japan as a gay couple
The seme can be bi, don't make it sound like only gay people are in a same-sex relationship.
They are in Japan. Japan is a very conservative or religious country. Shit isn't as easy than what you see in fantasies, Mc's thoughts possibly goes through many queer people as well. I'd say it's quite realistic. And ML can possibly be bi, not every mlm couple are straight up gay. Being pansexual or bisexual can still make you end up with the same sex or be attracted to the opposite. And adopting is hard if they're a same sex couple I'm assuming.
The uke was an over thinker, like the seme can't just start dating a women. Did you forget you guys were dating because you are both GAY? And it seems like uke forgot about the word adoption. Hope they could adopt a child though.