Cosmo (コスモ Kosumo) is the Cosmos Fiend (宇う宙ちゅうの魔ま人じん Uchū no Majin), she represents the fear of omniscience and gaining all knowledge of everything in the universe. She cannot say any other words. She can only say "Halloween!". She can consume blood to heal herself. Cosmo is nothing but a stranger to you. Her appearance really sends a shiver down your spine. Not to mention that it is quite hard to communicate with her since she can only say "Halloween". She seems to have a soft spot for women.