In the early spring of their second year of high school, Xu Xiangyang, his new neighbor girl, and the class president from the neighboring class share a common secret: they have broken into a real haunted house, solved a serial murder case together, and are raising a large, frightening pet that feeds on ghosts from another dimension. It's all like a huge iceberg hidden beneath the surface of everyday life, gradually revealing itself to the three of them. However, the future that awaits these young people is not always as novel and interesting as they imagine. In addition to the various worries of high school life, Xu Xiangyang soon discovers a new secret: the real name of his friend's pet is Angolmoa, the great demon king destined to destroy the world in an apocalyptic prophecy...