Be My Boyfriend, a spin-off of the popular web series, Best Mistake, depicts the story of Lee Seung Min, a boy with zero presence who is offered a contract relationship by Oh Ji Na, the best girl-crush idol trainee in the school.

• Shin Hyeon-seung
• Lee Si-woo
• Choi Yu-ju
• Lim Sung-kyun
• Kim Byeong-kwan
• Jung Bo-min