Wandering Witch: The Journey of Elaina

Finding herself out of money in the town of Rostolf, Elaina takes a job from a fellow witch named Estelle, who tells her about a friend named Selena: she lost her parents and was taken in by an abusive uncle until she went insane and murdered him, forcing Estelle to execute her. Estelle wants Elaina's help in a time travel spell to go back in time and prevent the deaths of Selena's parents. Elaina accepts and the two successfully travel to the past. However, while warning Selena's parents, they are attacked by the killer, who is none other than Selena herself. She reveals that her parents abused her as well and she never saw Estelle as a friend, prompting the latter to kill her. After returning to the present, it is revealed that Estelle gave up her memories of Selena to boost her magic, leaving Elaina to despair about the situation. (Source: Wikipedia)