Yesol, who consistently ranked at the top of her class, suffers a massive slump on the day of her college entrance exam, leading to a disastrous result. Determined not to fail again, she chooses to retake the exam, and her family hires a private tutor who attends a prestigious S University. That is how she meets her tutor, Yumin. Yesol begins her tutoring sessions at a place of Yumin's choosing, but under the guise of study, she finds herself receiving 'instruction' from Yumin's college friends, Seokhyun and Jongwoo as well...