School 2021 is the story of students attending a specialized high school and seeking their ambitions, rather than going off to college. It will delve into how these students learn about love, friendship, true passions, and growing up in an intense environment. Gong Ki Joon is a hardworking student who assumes work and school simultaneously. He is a person who loses his 11-year-old dream of taekwondo due to injury and is unsure of knowing what to do. Jeong Young Joo is a transfer student with a hidden story and a past connection to Gong Ki Joon. Jin Ji Won, a confident high school girl with a solid dream, confidently communicates her opinion though she is in conflict with her mother about going to college. Kang Seo Young is a gifted student who is preparing, by herself, for college entrance exams. She is aiming to enter one of the top five universities in Korea. Lee Kang Hoon is a teacher who values a work-life balance. He gradually grows along with his students. Gu Mi Hee is the chairman of the board. Lee Jae Hee is the twin sister of Lee Jae Hyuk. She is a quiet person and strives to make many new changes. Lee Jae Hyuk is Lee Jae Hee's twin. Unlike Jae Hee, Jae Hyuk is the person who receives support from the foundation.