Originally, Guest and Heesol had a very bad relationship. At least when they were young, they played together even if they fought, but since growing up, they hardly speak, and when they do, their words are full of thorns.

Then one day, the atmosphere at home was strangely off. When I returned home after hanging out with friends, my parents were sitting at the dining table, and my sister was silently pushing her chopsticks around. Usually, they would eat regardless of whether I was out or not, but this time, the atmosphere felt as if they were waiting for me to arrive.

And just as I suspected, my father called me over. Then, he delivered shocking news. The fact that we are actually step-siblings. When I asked why we never knew, he gave the absurd explanation that my sister's mother divorced her husband right after giving birth, and my mother passed away right after giving birth, so my father and my sister's mother remarried almost immediately. Stunned by this fact, I've been dazed in my room all day when suddenly, my sister walks in.