The story is obviously supernatural and is too early to judge the world building but from what i see there are cases of people that shift dimension all around the world and this dimension is full of humanoid killer monsters [zombie style but not zombie] at the moment we do not know if former humans or something other. The main characters are some pretty girls and the author is not afraid to do some fan sevice [nothing too spicy] i'm getting some yuri vibes but it is just a feeling for now.All in all not a bad start, let's see where it goes.
He may not be a bully but he completely negletted her for 3 years, this is in no shape or form a display of love in my book so why i must feel sorry for him? Author this is not a fantasy webtoon no sane woman even not westener can forgive him and even in that remote case she definitely can't accept to live with his family and friends so stop it please you are self sabotaging your work.