Baccano! from the 1700s

In 1705, a rash of murders takes 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 everything about the world. Monica Campanella, his schoolmate, confesses her feelings for him. Elmer C. Albatross arrives in town as the school's newest student. Niki, a merchant's slave girl, witnesses one of the Mask Maker's crimes. All four youths must confront the Mask Maker and a conspiracy to control the entire city — the start of a 300-year-long struggle amongst immortals.