Baccano! from the 1700s

In 1705, a series of murders occurs in Lotto Valentino, a city in Italy. The killer, known as the "Mask Maker," wears a white mask and places one on each victim. Those who see the murders are targeted next. Huey Laforet, a student at an alchemy-focused private school, harbors deep disdain for the world. His classmate, Monica Campanella, tells him she likes him. Elmer C. Albatross joins the school as a new student. Niki, a slave girl working for a merchant, sees one of the Mask Maker's killings. The four young people face the Mask Maker and a plot to take control of the city, marking the beginning of a 300-year conflict involving immortals.