This series feels like a joke. Like a publisher said "let's take the stupidest, most pointlessly grimdark edgelordy plot we can find that also has sub-standard or worse art to carry it and give them a serialization just to see if people will buy it, lololololol." and then they went out and got hammered and laughed at how dumb people are.
It's stupid pointless bleak shock value nonsense just for the sake of it. It's not interesting enough to be a parody or deconstruction of isekai stories. It's not well written enough to stand up as an unflinchingly dark but interesting story (like, say, Berserk). It's like some angry loner middle school kid saw Game of Thrones, equated its sex, gore, brutality, and depravity with being "mature" and then put pen to paper with that warped vision as their goal.
Someone mentioned Parallel Paradise, which is gore fetish nonsense masquerading as having depth, but at least the artist has some skill there. Not enough to make me read it after I quit around the 40th chapter or so because I could not muster up enough give-a-damn to care about the characters when they seemingly exist solely so said artist can jack it to his gory carnage, but he does have some skill. This might be the new clear winner whenever someone asks me "what's the most objectively bad thing you've ever read?" Because this is not just me rejecting it because the content is not to my subjective tastes. This is about it failing on multiple levels of story and artistic craftsmanship. I rarely ever rate stories I've read as "1" but holy balls this is atrocious.
If i was an editor at the publisher for this story I would be embarrassed that our standards are so low that this gets a place in a magazine or on a website.