Call it edgy if you want, but I certainly find the twisted voice of lust to be realistic to a degree. It's OTT but in reality when you get fantasies or desires that are hard to control, especially when you're young and full of hormones, it's pretty crazy.
Maybe people with lower sex drives or something don't get it.
I don't find Seiji unbelievable. He's crazy, but in ways that are, sadly, painfully common. I'm not reading this to find good representation or something, from the first this has been a trashy sort of manga about damaged people, and that's what I expect. That it delivers. If you want Morishima Akiko fluff you don't read NTR.