Baccano! - from the 1700s

In 1705, a rash of murders took place in Lotto Valentino, a provincial city on the Italian peninsula. The murderer, who wears a pure white mask and places one such mask on all of their victims, is known as the "Mask Maker," and anyone who witnesses their murders becomes their next victim. Huey Laforet, a boy who attends a "private school" for alchemy, hates the world. Monica Campanella, his schoolmate, confesses her crush to him. Elmer C. Albatross arrives in town as the school's newest student. Niki, a girl enslaved by a merchant, witnesses one of the "Mask Maker's" crimes. All four youths confront the Mask Maker and a conspiracy to control the entire city and this is the beginning of a 300-year-long immortals' ruckus.