This story is about a high school girl named Kim Ji-Won.She is now 18 years old with her twin brother Kim Myung-Soo(L). Ji-Won has 4 Bestfriends forever since she was a kid.The name of her bestfriends are Krystal Lee,Oh Min-Young,Park Hye-Gyo and Kim Yoo-Ra. These bestfriends have their twin brothers. The twin brother of krystal Lee is Lee Min-Ho(Main Character) while Min-Youn's twin is Oh Sehun and Kim Yoo-ra's twin brother is Kim Woo-bin.Song Hye-Gyo is special because she is the only one Ji-Won's bestfriends that has a twin sister named Song Ji-Hyo.The girls created a group of them includin Song Ji-Hyo called The Royalettes while The boys also created a group named The Royalness Boys. But The Royalness Boys has more members than Th Royalettes. The members are Lee Min-Ho,Kim Myung-Soo,Oh Sehun,Kim Woo-Bin and D.O.The royalettes member and the royalness boys member coupled for a year. Suddenly,When they were 18,there's something happen with these couples. They've tried many ways to secure their relationship.