I Messed Up and Made the Wrong Person Into a Magical Girl!
Manga
Machimaho: I Messed Up and Made the Wrong Person Into a Magical Girl! is a Japanese manga series written and illustrated by Souryu. It has been serialized on Shinchosha's Kurage Bunch website since October 2016; as of October 2026, fourteen volumes have been released. The story, set on modern day Japan follows main protagonist Kayo Majiba, a chain-smoking delinquent highschool girl who was turned into an all-powerful magical girl by a creature named Kyu in her walk to school.
Description from Wikipedia, available under CC BY-SA 4.0. May be shortened.