Choi Chi-yeol is the most famous math teacher in Nokeun-ro, the mecca of college prep students, and called the "Billion-Dollar Man" with his skyrocketed salaries. He is on top by being harsh and resilient, but he barely has time to eat and is always nervous about losing his top-tier status. While suffering from sleep and eating disorders, "National Side-dish Store" captivates his delicate taste, and he becomes more curious about the store. Giving up her career as a national handball athlete, Nam Haeng-seon became a late bloomer as a college prep student's mom to make up for her shortcomings as a mother. However, her attempt to build up a student-teacher relationship based on education with him fails