Very nice series.
I am not claiming to know Japanese culture, but from what I've seen in yaoi mangas and my own research online, the book follows the legends and customs closely.
The story also addresses trans* issues and explains them beautifully.
Though there is some violence present, it's not over the top.
I can't wait for the third book to come out. Hopefully, I will be able to pass this book to my 7th grader :)