Ano Oni Kyoushi ga Boku no Ane ni Narundesuka?

A boy is thrilled when he learns his father is remarrying and he’ll finally have an older sister. But his excitement quickly fades when he discovers his new stepsister is none other than Shina, the strict PE teacher from his school. With his father moving in with his new wife, the boy is left to live alone with Shina. As they adjust to their new life together, he’s surprised to find that the stern teacher he knows at school is actually clumsy, afraid of bugs, and surprisingly kind at home.