Heesu in Class 2

18-year-old Hui Su is an ordinary high school student who considers himself a “dating expert,” though he has never been in a relationship and has been single since birth. Secretly, he harbors feelings for his best friend of ten years, Chan Yeong, but keeps this heavy secret to himself, nurturing his feelings alone.

Meanwhile, Chan Yeong discovers that his favorite singer, Summer, is actually Ji Yu, a fellow student at their school, and he starts showing interest and developing affection for her.

Feeling a sense of crisis at this unfamiliar side of Chan Yeong, Hui Su teams up with class president Seung Won, who has a crush on Ji Yu, to win back Chan Yeong. However, for some reason, Seung Won seems more interested in Hui Su than in Ji Yu.