Growing up with your best friend

Must be the happiest moment of your life,

But falling in love with them

Must be the hardest challenge you'll

Encounter in your entire life.

Rule No. 1: Don't fall in love with me.

"Omo, Ssantokki! Of course I won't fall in love with you. I only see you as my best sister I never had."

"I know that Chaerin ah, but we both know that I'm undeniably gorgeous, and you might fall for me."

"And you know that I'm also undeniably hot, Ms. Park."

I know baby Rin. That's why I fell for you, but we're not meant to be and that's the truth and reality.