A really nice horror anime with some loveable moments strewn in as expected of Rumiko Takahashi.
Since I read (and loved) the manga about 10-15 years ago it was nothing new storywise but if you don't know it you might find it full with suprises.
I liked her version of mermaids quite a lot since it's nothing like the European version. Also I enjoy her more "serious" stories like this one.
All in all it's a great tragic story which offers violence and gore but also friendship and love.