The story follows Sakamaki Izayoi, a boy bored with the entire world. One day, an envelope arrives for him. The moment Izayoi opens the envelope, he is transported to an alternate world. There, he discovers that two other problem children were transported by envelopes as well — a taciturn girl named Kasukabe You with a cat, and a beautiful yet haughty girl named Kudou Asuka. A girl named Kuro Usagi (Black Rabbit) summoned the three to the community No Name to overthrow the devil.