Kagero - Kokumeikan Shinshou Japan

Enter a world where humans and creatures called Timenoids coexist. These blue-skinned Timenoids are determined to wipe out the inferior human race, and this is where you come in. You play the role of Millennia, a young woman who was brainwashed at an early age to do the Timenoids' bidding. She now believes that the humans must be exterminated from the world, which is rather ironic, since she is human herself. Yet if she succeeds, the Timenoids have promised her immortality and the power to become one of their own...