The plot follows a class of high school students attempting to overcome the stress of being ranked by their exam grades, and facing the difficulties of being a teenager in a high-pressure, corrupt system. Its central protagonist is Ra Eun-ho (Kim Se-jeong), a cheerful and kind-hearted 18-year-old who dreams of being a webtoon artist but is caught up in the search for a mysterious troublemaker in the school, known as 'Student X'. When she is accused of being Student X, her dream of going to university to study art is put at risk as she faces expulsion.