Machimaho

Machimaho: I Messed Up and Made the Wrong Person Into a Magical Girl! (間違った子を魔法少女にしてしまった) is a manga written and illustrated by the mangaka Souryuu and published by the Shinchosha publishing house in the Kurage Bunch magazine from October 7, 2016 to the present, counting so far with 7 volumes.

Plot
While searching for a brave candidate to become a magical girl and defend the world from evil, a mythical creature finds Kayo Majiba, a cute young lady who seems like the perfect fit. But when this newly turned magical girl proves to be a crude delinquent who goes berserk in a conflict, it becomes clear that this may have been a terrible mistake. Now evil—and any innocent bystanders—will face the rage of a magical girl gone wrong!

Official

 * Shinchosha

Other Sources

 * Manga: