The scriptwriter is inspired by the Incheon Elementary School Murder case in 2017. In 2017, at the Incheon Elementary School murder trial, when the victim's mother asked the defendant what was the hardest thing right now, the defendant's answer was not sorry or guilt. Instead, the defendant said, "The weather is nice, but it's the hardest for me not to see cherry blossoms." The whole nation was shocked and furious at the defendant's response.
The story of this series is based on concept of the "Psychopathic Gene". Psychopaths have the same brain as ordinary human beings, but without a mirror neuron. They do not feel the pain of others at all. Neither can they perceive other feelings such as guilt, sympathy, compassion, or regret. The scriptwriter planned the drama in this backdrop.