"You are crazy."

  "Yep,I am. All because of you."

  What happens when Kai don't want to be just Taeyeon's reliable brother or good friend.

  Taeyeon was adopted by the Kim family and Kai became her older brother. As time goes by,Kai doesn't simply want to be just Taeyeon's brother and started to violently object her dating his best friend,Sehun.This is starting to spoil their friendship especially when Kai does absurd stuff that annoy and irritate both Sehun and Taeyeon. They soon forgive him as they thought he was just being a over protective older brother..or so they thought so..Will Seyeon survive or Kaiyeon?And what would their parents think about Kai's crush on his adopted younger sister?

Kim Jongin also known as Kai

He is 25 years old this year.

He is Taeyeon's older adopted brother.

He is Sehun's best friend.

Kim TaeYeon

She is 22 years old this year.

She is Kai's younger adopted sister.

She is dating Sehun.

Oh Sehun

He is 25 years old this year.

He is Kai's best friend.

He is dating Taeyeon.