If you can get past the gore descriptions, the kinda skeevy age-gap relationship, and Ryuukishi07's prose style, "Bakemonotachi ga Usobuku Koro ni" is a pretty fun romp, and one with a message of empathy.
NOT a good first japanese novel unless you are in a hurry to learn how to describe various gross smells
My opinion on the actual work is kind of mixed but I also feel like my jp level was below ideal for this, and any review would be unfair. Not to mention, it took me about 2 years to read, which also isn't ideal for a decent review.