Fullmetal Alchemist: Homunculus

Sin was the first Homunculus before Hohenheim, she was resurrected by him, but was quickly sealed away in a chamber that Hohenheim created, due to her intense craving for blood. She was Hohenheim's first way of creating Philosophers stones, by having one a sacrifice enter her chamber and extract a vile of her blood. They always managed to get her blood, but before each one of them could escape Sin had dragged them back into her chamber and are brutally killed them. So later on Hohenheim decided to place her in a straight jacket and a steal plated mask to prevent her from killing them, but his efforts were futile, she couldn't be stopped.

Sin has no feelings, she lives off of the deaths of others. Even when there is no sacrifice to retrieve her blood, she sings a demonic song that only the person that she wants to kill will come to her by her control. For which Hohenheim made a thick barrier around her that was sound proof to prevent her from killing them when they weren't needed. So she is forced to wait for a sacrifice to come to her, which the time between each is about a entire month. Which makes her frisky and her craving for blood rises.

Every vile is what created the other Homunculi, which one single Philosophers stone was created by 56 viles of her blood. Each vile contained the amount of blood that was in a elephant, which didn't affect her when it was drained, only makes her scream and go insane. For each Homunculus they were told that Hohenheim created them with his own hands, but never told them about Sin.

So now a couple hundred years have passed, as war broke out. The other Homunculi, Edward and Alphonse Elric, and the rest of the country will now know who was the first Homunculus and original origin of Philosophers stones. But who knows how that will go, when Hohenheim unseals her from her chamber.