When you grow up, marry your older sister

*This work is a romance. Kim Yeo-joo, 22, the main visual of the most popular idol group and the world's prettiest and most talented, and Choi Yeon-jun, 18, a popular, handsome man at school and known for his stubbornness. Yeo-joo has raised Yeon-jun since childhood, and although they're not dating, they've become indispensable to each other... What will be their fate?