For over a thousand years, humanity has been protected from the relentless invasions of monsters by the strongest grand mage, Ishtar, and her exceptional direct disciples. However, among these disciples, only Gilberto led a self-indulgent, lazy lifestyle. One day, Ishtar suddenly announces her retirement, and a young girl named Lapis appears, aspiring to become a disciple. As one problem after another arises, Gilberto's peaceful days are turned upside down—!