Anything French. Anything at all. The human body isn't so taboo in France and neither is sex.
(God help you if you bring up abortion tho)
There's a great fun comic called Luuna , which seems to be about 90% for kids, then in the same volume (SPOILER WARNING) she goes topless, gets possessed, rips out her best friend's heart, returns home to find everybody murdered and sells her sole to the God of Darkness for revenge.
I'm fairly certain you can find that under "jeunesse" (youth).
Caste of the Metabarons is another one, it's matter-of-factly blithe not only about sex, but about sexual taboos (such as incest).
La Campagnie des Glaces (The Ice Company, but sorry, no English release) is far more restrained than the books, and it still deals with all kinds of stuff, from sex to incest to cannibalism and it doesn't hide anything.