Hyeong-Cheol Kang	...	(Director)
Hyeong-Cheol Kang	...	(Writer)
Ho-jeong Yu	...	Na-mi
Eun-kyeong Sim	...	Young Na-mi
Hee-kyung Jin	...	Choon-hwa
Min-yeong Kim	...	Young Jang-mi
Su-hee Go	...	Jang-mi
So-ra Kang	...	Young Choon-hwa
Yeon-kyeong Lee	...	Geum-ok
Bo-ra Nam	...	Young Geum-ok
Seon-kyeong Kim	...	Bok-hee
Bo-mi Kim	...	Young Bok-hee
Jin-hee Hong	...	Jin-hee
Jin-joo Park	...	Young Jin-hee
Hyo-rin Min	...	Young Soo-ji
Yeong-seo Park	...	Jong-gi
Seung-hyeon Han	...	Jang-mi's older brother
Jun-seok Kim	...	Composer
Na-young Nam	...	Editor

Summary: New high-school transfer student Na-Mi (Shim Eun-Kyung) comes from a small town in Jeolla Province to her new school in the capital city of Seoul. When she is nervous, her small town dialect comes out & she starts to shake.On her first day at her new school she is bullied by others. Coming to her help is a group of girls. The girls are Chun-Hwa (Kang So-Ra) - known for her strong sense of loyalty & excellant fighting skills, heavyset Jang-Mi (Kim Min-Young) - who badly wishes to have plastic surgery to get double eye-lids, Jin-Hee (Park Jin-Joo) - excellent when it comes to spewing profanity, Geum-Ok (Nam Bo-Ra) - interested in literature, Bok-Hee (Kim Bo-Mi) - dreams of one day becoming Ms. Korea and Su-Ji (Min Hyo-Rin) - always arrogant. Na-Mi quickly becomes part of their group. When the group confronts rival girls known as Sonyeo Sidae ("Girls Generation"), Na-Mi spews curse words she picked up from her grandmother. Because of Na-Mi the girls are able to avoid a crisis.

These seven girls then form their own group named "Sunny". They also vow to stay together forever. The girls then prepare for a performance at an upcoming school festival, but on the day of their performance a terrible event occurs leading the girls to eventually going their own separate ways.

Twenty five years later, Na-Mi (Yoo Ho-Jeong) is married to a successful businessman and has a beautiful daughter. Her life seems perfect from afar, but there's something lacking in her life. One day, Na-Mi bumps into high school friend Chun-Hwa (Jin Hee-Kyung) in the hospital. They are ecstatic to see each other, but Na-Mi receives a phone call and has to leave. On her way out she ask Chun-Hwa if there is anything she can do for her. Chun-Hwa at first says no, but after a moment of reflection she makes a simple request to Na-Mi. Chun-Hwa asks Na-Mi to find the other members of "Sunny," so she can see them one more time ...