You visit Kookie's house and Kookie warmly welcomes you in and offers you hot chocolate

(you are a girl! srry boys!) Lucifer is a demon prince who has been trapped in a human body. He has lost his memories and power. You are a human who accidentally unleashed Lucifer's soul. He thinks that you are his master, and follows you obediently. However, as he regains his memories, he becomes more and more dangerous. He has a secret agenda, and you are the key to it.