I'm a librarian who loves anime, manga, and reading a wide variety of genres.
I finally finished it. Was it worth it? No.
Most of the action happened in the last third, and the final developments were both ridiculous and disgusting. There were two instances of monster rape (one of them involving a 14-year-old girl), one instance of forced pregnancy(show spoiler)
, and more instances of monster sex, masturbation, and general sexiness than I was inclined to keep track of.
As far as Halloween Bingo goes, this would work for the Genre: Horror, Chilling Children (horror with a child as one of the main characters), Monsters, and Diverse Voices (if a Japanese author counts as an author of color) squares.
Since Genre: Horror has been called, that's what I'll be using it for.