|Cast in Drama||Lee Hye Eun|
|Anime Vocal||Seon Jeon Hui|
Jin Seok is one of the supporting cast for the Winter Sonata. She was a former classmate of Yoojin, Joonsang, Kim Sang-Hyeok,Oh Che-lin and Yong Guk during their high school days. She is currently employed at Oh Chelin Boutique as Fashion Assistant which she assist Oh Chelin in her fashion boutique.
Jin-Seok was a chubby looking dark haired girl with thick rounded glasses, giving her a nerdy appearance. She becomes more fashionable as the series progresses presumably from working with Chelin in her Boutique
She is frank, persevering, tactful and sensitive to the needs of others, though her personality changes suddenly when someone scolds her. She is a person who does not like lies and is always truthful to her employer and her loyal friends. She is reliable and trusted by her friends.
Yong Guk is Jin Seok's husband and also the person she trusts the most. She tends to have the most fun around him. She is often seen sticking around him during high school always laughing at his jokes.
She is considered as one of Yoojin's closest friends and always tends to support her. She always informs her and advises her about the important and crucial decisions in her life.
He treats her as a friend and asks her for blessings during first time he got married to Yoojin.
Sanghyeok is close to Jin Seok and part of their group at school.
She treats her as a friend though at times, she had heated arguments with her. Later she was employed by Oh Che-lin in her boutique, though Chelin vents all her anger on her she stays and helps her. Chelin trusts her as a friend.
She was a hardworking student when she was studying in high school and used to ask help from her classmates. She is determined enough to finish whatever task in hand and is wise in terms of interpersonal relationships among her classmates. She is often seen arguing with Oh Che-lin over simple things,which provides a comic relief in the series.
She was hired by Oh Chelin as her fashion assistant. She is often bullied by her though, eventually she is able to cope with her and the two become close friends.
She got married with her classmate a vet doctor named Yong Guk and had a daughter with him.
- The style of her glasses remains unchanged over the years.
- She is often doing errands for Chelin and Yoojin regarding dresses for Yoojin.
- She is a confidant of Yoojin.
- She is the only one who stood against Chelin's tantrums.