This is a spoiler free review for the whole series, up to where it is currently out in English volumes (volume 21). I update it periodically as I don't like rating individual volumes and would rather rate the series as a whole. 

I originally picked up this series as I was intrigued by the art style, and lets face it the weird title, but I stayed for emotional character development and engaging mystery plotline. There is so much to this series that I think people will enjoy, I certainly do.