The Witch of the West Is Dead by Shunichi Nagasaki

7.20

A 13-year-old girl named Mai refuses to go to school due to her asthma. Her parents send her to to stay with her British grandmother in the countryside. Thinking her grandmother is a witch, Mai asks for witch lessons. Her grandmother plays along, but instead ends up teaching Mai lessons which help her become more responsible and enjoy the simple aspects of life.