Sakura in the normal version wants to bury Misaki alive for wanting to have sex with her brother, but in this version she even wants to share, it seems that their sexual frustration makes them much more possessive.
I'm surprised, from what it indicates Hinata actually had a father, a man in this world who really wanted to have a child with another woman, how sick in the head her mother must be which apparently scared the guy and made him never want to see her again.
Compared to the R18 version, progress in the story and the time between the release of each chapter is slow, sometimes I think the author planned R18 as the main series, but released a lighter version first to attract an audience and it worked.