For nearly thirty years, human beings have become difficult to control their own emotions, which is called "emotional disease". At the age of ten, because of the blow of his father's death, Chang Mo began to be able to see the "cyst" produced by emotions on the heads of ordinary people. Later, because he witnessed his mother's death due to the explosion of the "cyst", over the years he has always suppressed his emotions to ensure absolute "rationality" so as to avoid contracting emotional disease. Until the day of the cruise ship team-building, Chang Mo suddenly discovered that he had long ago been infected and called a "rational" emotion monster!