Kuchisake onna
This happened so because she used to be so beautiful that everyone in the late 90s used to dream her. One day her samurai husband went on a war and she started an affair with a young handsome young man. When he returned he found his wife having an affair with another person. So, he took his sharped sword and divided her face in to two halves through lips. This made her too ugly due to which no one ever looked her again. The pain was that insane which made her commit suicide. From then on she started a journey make her like that.