In a modern world, a professional assassin was murdered by her beloved and found herself revived in an ancient world as a general's daughter with a weak physique. She was engaged to a prince, but because she did not have a nice appearance, her fianc and sister attempted to kill her. Although she had to struggle to survive, there were also those who unconditionally loves her that supported her in her time of need.
She is a top-class spy, a poison specialist, but also a young and cute girl with a sinister temperament. In spite of her sweet and innocent appearance, she can complete any tasks without the slightest hesitation. One day because of an incomplete black magic, she was sent into the body of a girl who was deemed as a good-for-nothing. What kind of change will she bring to this continent?