Taeyeon has always been regarded the princess in her family. Her parents, Yunho and Kahi. they have four sons, Leeteuk, Nichkhun, Eunhyuk and Kikwang. the were considered as flower boys. Every girl in their neighbourhood, school, workplace or even strangers that walk past them immediately feel for their looks. they each have nicknames. leeteuk being the smiling angel, nichkhun being the winking angel, Eunhyuk being the y angel and kikwang being the cute angel. Although Yunho and Kahi loved their children but they always longed for a girl. they have decided that if their next child is a girl, they would name her Taeyeon. After one year, their dream came true. they gave birth to a baby girl. 

but... deep within their house, a deep secret lies within. Actually, Yunho and Kahi are secret agents. they were kicked out from their own company because they are not suppose to fall in love with each other. they set up thir own company called 'k'. it was a famous company, many customers asked for their help. their agents were of course their children. Yunho and Kahi planned to close down the company bacuse they didn't want tocontrol Taeyeon's future. they wanted her to have her freedom of chossing. but a thing that taeyeon did changed their decision. when taeyeon started to learn how to walk, they came to their personal shooting range. they grew up with guns so they were not afraid of it at all. taeyeon even treats it as her toy. she stood up on the table and shot bull eyes into the target. Yunho and Kahi was pleased to see that taeyeon has such a talent and decided to train taeyeon up as a secret agent too. 

15 years has passed and taeyeon has a better control of knifes, guns than her brothers. she defeated them in Taekwando. her parents were very pleased wih her performance. she is good in studies, sports, it, weapons and self defence but there is a weak point with taeyeon. she is very naive, innocent and easily persuaded. there has been a number of plyers to try to seduce taeyeon but they never succedded once. their common pick up lines or tricks that usually would make a girl blush but nothing of this stuff worked on taeyeon.instead the players fall for taeyeon because she was really special. she did nothing but smile which make guys faint. but she was always oblivious about her popularity. because of her naivity, her brothers would protect her no matter what happens.they all go to the same schoolbut they never hanged out together because she wanted to be a normal student but with her brothers popularity, it was not possible so she hanged out with her best friend yoona which is also a agent because their parents are very close to each other. yoona and taeyeon were really popular but because they are poblivious to their surroundings, they don't notice their popularity at all. taeyeon was called the school's cutie pie while yoona was the school's y diva.

taeyeon life seemed to be very prefect but a series of events would probably cause probelems to arise within their happy family...