Fungi have taken over humanity. They attach themselves to the brain and rob them of their free will and thought, creating a society ruled by fungi. But in this “utopia for the fungi,” an irregularity was born. The strongest soldier, Dante, decided to fight back against the world's norm after meeting a young girl called Aoi. Can a species live in harmony with another that has different ways of thinking and ideals? After Risa, the girl with the bear mark, joins Dante's team, the resistance finally decide to enact the Beelzebub strategy. But Amigasa won't be letting them do so without a struggle. During the intense battle, Either receives a creepy warning from a third party outside of the Amigasa and Ether factions. Are they friend or foe? Here starts the Red Fang arc!