Arnold is a popular online erotic fiction writer famous for his ‘Sex with senior student’s girlfriend’ and ‘Friend’s older sister series’. However, he is writer Dong-myeong (Choi Jae-hwan) in reality, who dreams of winning the New Spring Literary Contest and works as tutor at a preparatory school to make a living. One day, his first love So-yeon (Wang Bit-na) appears in front of him. She claims the copyright of his novel, ‘Sex with senior student’s girlfriend’ and asks him to share the profit he has made from the novel so far.