Pest ga Aketara Asobimashou! Chuusei Europe Sekai to Gendai Bunmei Slow Life

Synopsis

Medieval Europe has been plunged into the dark ages by the spread of the Plague. Rachel, who moved to this rural town, meets a "witch" who can wield mysterious tools. The "modern technology" she uses seems like sorcery to a person from the Middle Ages...? (Source: Kadokawa, translated)