Boy-Friend's Rule summary: Jiun's first romance ends when her crush, Jae-i, confesses that he likes someone else. To make matters worse, Jae-i mistakenly believes that Jiun's crush is his scary-looking best friend, Seohyeon, and tries to help her win him over. Now, Jiun must deal with a bigger problem than her unrequited crush, the boy-friend she had never imagined getting close to.