From what I'm seeing, and I'm no expert on anime by any means, but "she's" not human. Saying this is wrong seems like the same thing as saying it's wrong to breed a snake because "it's only 10 years old". Seems relative to me. Unless she's being portrayed as a child, 10 years in mythical years may be 25 in human years?
Eh. Just my 2 cents.
I don't given a fly flip is she's a 10 year old person, vampire, or mutant ninja turtle. She looks like a 10 year old and is portrayed as such.
Edit: Never mind. Just go to themanime.org and go to the review.