Embalming Magic: Mahou wo Korosu Mahou

A girl was hit by a car right in front of my eyes. That day, for the first time, I used magic on an ordinary person, knowing it was taboo. She was saved, but since I'm terrible at magic other than "destruction," I turned Ieiri Nagi into a cat. Humans who are "possessed by magic" will turn into monsters if they do not learn to use magic. Source: MU