This is one of those titles that oozes that unique, strange imagination that niche, Japanese manga is known for. Other titles like this are BLAME! and that Yakuza/gender bend/isekai one. Just chock-full of interesting concepts and appealing art.
Definitely worth a read and one of the freshest things to come into manga in general in a while. This is the "not as happily ever after" story to an isekai that still tries to be hopeful.
The rest is an explanation as to why I think the ratings are so polarized.
To be honest, as a 30 year old virgin who hasn't really found a real woman to be interested in, there are several times this manga irks me in a way that's uniquely my fault... and I suspect people like me is where a lot of the hate is coming from.
The main character (MC) gives up more than half his life to save another world, finds out the two women he traveled with fell in love with him, then out of love, then in love with the two guys he was traveling with. All as he's returning home (and yes, they are officially dating—the one pair was getting married).
Then he gets home and finds out his childhood friend is used goods.
Or, that's what the immature side of me wants to say. It's a situation I fear, that the woman I one day get interested in has had other guys and I'm not going to be the one who can give her the best pleasure. Call me a romantic, or a loser, but that's how I feel. (For the record, a sudden and unexpected medical condition has put me in this situation for the past 7 years.)
And it's not entirely right or wrong to feel that way. But it also causes me to empathize with the situation in a way different to those who can get past these kind of hangups and freely enjoy this manga.
The MC has issues with the various kinds of love, and that's explored through this. His feelings for his childhood friend and first love are reappearing. This is honestly, for this situation, not a bad thing. But I don't think it's wrong to feel like he did his time and got shafted like those Jody stories in the military.
It's why I secretly hope the MC does get to be with her daughter, however right or wrong that may be (supernatural creatures and fighting for one's life kind of blur those lines in regards to maturity and appropriate age; but IRL it's definitely not right).
I see a guy who gave everything and is getting second-best despite his efforts and achievements. Now, that's both true in one sense and completely false in another for this story. He wasn't actually cheated on, but he certainly was prevented from his fair chance.
So yes, the MC does actually grow up, mature and get happy with his life, but my feelings are upset for him because it wasn't fair and because I am seeing my fears take place in a story.
Would I end up able to forgive my situation and learn to live my best life in a situation I may be heading towards? I would hope so. I would also hope to find someone who wasn't settling for me, but who actually desires me.
But that immature part of me intersects unusually well with the high moral standards I set for myself and the woman I hope to one day find.
Thus, a legitimate reason to not like something also fuels that innermost childish yearning to deny parts of reality that are harsh and unfair which creates something ugly because a bad thing (denial) is justified by a good reason.
That's my theory.
Anyways, I have been able to separate the two and enjoy this manga. I'll be happy for the MC and take a step back to realize I need to keep the high morals without twisting them to justify immature yearnings. And I hope everyone from incels to regular people will learn something.