This drama tells the story of Class 300, a private school in Eto, where % students with zero motivation, zero talent, and zero future potential gathered together. They ushered in a new class teacher. He has a good appearance, but is a little weird.Teacher: Rei Kagami.The common sense in the school no longer applies. His assets and mobility are ridiculous. His true identity is that he inherited the CEO of the chaebol group that represents Japan and is an unexpected billionaire.Although times have changed, the problems of adolescent children have not changed at all.Kagami, the new hero who breaks common sense, faces various problems and grows up with the students here.​