
Min-seok, who was taking a math tutoring class from Yu-ri through the introduction of his older brother Min-woo, caught Yu-ri when she stops masturbating. After that, the two start tutoring awkwardly with each other. He witnesses Min-woo and Yu-ri having sex in the living room, feeling betrayed by Min-woo and Yu-ri, who he secretly had a crush, Min-seok asks Yu-ri to have sex as an excuse.