Well, at least they explained why she imagined her brother raping her so it's fine ending, I guess.
Honestly, it feels like the author didn't really know what the fuck was going on at first and came with the coma thing later on, but I haven't properly analyzed this so I can't say that for sure, shit like the blimp being seen as a monster or her "friends" dissapearing and then reappearing was weird as fuck and never properly explained (thoug we can assume the dead and the living saw things in a different way and the dissapearing incidents were due to Tatsuya or the brother's interference).
I did like the twists about the brother being the good guy all along and her "friend" being the "bad" guys, I legitimately didn't see that one coming.