Might be slightly explicit stuff in the opening song.

A few shirtless males.

There is a ball in Episode 11 and some of the attires there might be somewhat revealing.

One bath scene, though not very explicit.

Considerable number of romantic scenes.

Lot of blood sucking, fangs and other vampire stuff. Fair amount of violence. Some battles can be quite bloody. Some terrifying deaths. Bloody pools and bloody clothes. Some intense wounds

4 uses of Bastard.

A man smoking. Vampire pills that can be considered drugs to make yourself at ease.

Some vampires can be quite scary. (Lv-E). Quite some suspense. Frightening amount of blood.