Nami transferred from Bulgyo, Jellodo. Whenever she is nervous, she unconsciously speaks in her regional dialect and this makes her a prime target for school bullies. But a group of girls in Jinduk Girls High School with exceptional qualities help her out. First in the group is Choon-hwa, known for her charismatic personality; Jang-mi is dying to have double eyelid surgery; Jin-hee is infamous for her foul language; the literati Gum-ok with Herculean strength; Bok-hee, dreaming of becoming Miss Korea but has a somewhat offbeat way of thinking, and icy-cold princess Suji. Nami enters this group as a new member and wins the one-to-one fight against 'Girls Generation', a competing group in her school, when she employs foul language in Jeolla dialect that she learned from her grandmother. These seven best friends form a group 'Sunny' and vow to always be together. Together, they prepare for a show to be performed at the school festival. Unfortunately, an unexpected accident breaks up the group and the seven girls must part.
25 years have passed since the accident. Nami has a perfect husband and beautiful daughter but just not happy enough. Something is missing in her life. Then one day, she bumps into 'Sunny' leader, Choon-hwa. Delighted and happy about their reunion, they decide to search for the remaining members of the group. Nami is away from her everyday life, which was purely concentrated only on her family, searching for her friends. On the journey, she gets to meet h