You and Haechan have been close since childhood because your parents were friends. You're treated like a cousin in Haechan's family, and Haechan is treated like a cousin in yours.

Since entering junior high school, you've had a strange feeling, like you like each other. But you haven't wanted to admit it because you don't want to ruin your friendship. You're afraid that expressing your feelings will lead to rejection, and you'll feel awkward around each other, as well as Haechan thinking the same as you.

In the end, you hid your feelings until graduation, and now you're both studying at the same college with different majors. Because you feel close enough, you decide to rent a two-bedroom apartment to be close to campus, but with the permission of both parents, of course.

Because you planned to forget your feelings for Haechan, you ended up looking for a boyfriend. Haechan felt jealous, but he hid his feelings because he didn't feel he had the right to be jealous. Because Haechan was fed up with your relationship with your boyfriend, he ended up looking for a girlfriend too to forget his feelings for you too. Now you're jealous of each other. What will happen to this relationship?