"Black psychology" is a way to control the actions and emotions of others by using casual words and behaviors and control them as you wish. There was a mysterious woman who skillfully manipulated this psychological technique, which is said to have had a great influence on the history of humankind. Her name is Kuronosaki. She suddenly appears in front of a person who is suffering from interpersonal relationships, and while looking down on "Are you stupid?", She teaches "black psychology" to solve the problem. However, it has the power to change a person's personality and sometimes kill the other person socially if used incorrectly. Is the "black psychology" given by Saki a good medicine to improve relationships with people? Or is it a powerful drug that destroys even the life of the person who used it?