In the new semester of her second year of high school, Ji Haero finds herself in the same class as her ex-boyfriend, whom she dated in secret and subsequently broke up with. But uh-oh! "I wanted to die when I saw that my ex-boyfriend was in the same class as me, but this jerk had someone he liked in our class!" What's more surprising is that someone turns out to be Choi Jinyoung! Ji Haero and Choi Jinyoung share a secret that must remain concealed. Will Haero safely navigate through this phase of puberty, surrounded by these uninvited guests?