Saint Marguerite Academy is a lavish boarding school in Sauville, a Southern European country where Kazuya Kujou is a foreign student. Despite originating from Japan, he is ostracized by his peers due to his jet-black hair and dark brown eyes, earning him the moniker "Black Reaper" after a local legend about a deadly traveler in the springtime. Although Kujou initially visits the school library for ghost stories, he becomes entranced by a golden hair strand he discovers on the stairs. Following the steps, he reaches a grand garden where he encounters a stunning doll-like girl referred to as Victorique de Blois. With her complex and ingenious foresight ability, she predicts their intertwined futures. As more puzzles emerge, including a phantom ship and an alchemist with transmutation powers, Victorique and Kujou are destined to rely on each other to solve them, bound by their fate and extraordinary talents.