Help me finding a manga!

i read this manga a while ago, it was about a family of aristocrats who were seen as "perfect" in terms of blood, skin, etc. And chimeras/demons annihilated them to consume them. The only survivor, a boy made a contract with one of them, a demon woman, but only if the she killed the others there. I believe the name is no. something (the demon name,) but can't find it anywhere!