Yujin is a nerd who loves Choi Beom, his senior who is in the same department. Because he is shy and does not dare to express his feelings, it makes him often dream of Choi Beom. Then one day, Yujin got into his grandfather's potential-making machine, and because of the machine's malfunction, a bitch personality was born. "Why are my eyes covered!" "Sunbae, do you know that I often dream of having sex with you?" Let's follow the story of the Nerd and Bitch personalities surrounding the handsome and cool senior.