Hoshikamo yearned to become a private detective and he now works as a private detective. He is not good at communicating with women. Hoshikamo once worked at a big private detective agency, but he now he runs his own private detective office. His office is situated within his grandmother's recycle shop. Hoshikamo solves various cases with his assistant Tsugumi Karato. He first met Tsugumi Karato when she was his client. She hired him to help her with a stalker.
The forbidden technique of "Dark Psychology" is a method of using casual conversation, hints, words, and behaviour to manipulate the thoughts and emotions of others to control them as you wish whether that be to good and innocent ends or to satisfy even the darkest desires of the heart.