Lord of Vermilion - The Crimson King

"Lord of Vermilion: The Crimson King" (also known as "Lord of Vermilion: Guren no Ou" in Japanese) is an action fantasy anime series based on the arcade trading card game "Lord of Vermilion" developed by Square Enix. The story is set in Tokyo, which is isolated by a strange event known as the Great Collapse. Everyone within the city falls unconscious, and when they wake up, they find that a blood red mist surrounds the city, cutting it off from the outside world. College student Chihiro Kamina and his friends find themselves in this cut-off city. Soon, they discover they have the power to summon entities known as "familiars," gaining the ability to manipulate the red mist. However, this newfound power puts them in the middle of a conflict between two factions: those who wish to break the isolation and save Tokyo, and those who want to keep it isolated for the survival of the world.