Claim: Girls' Generation has girls.

Seo Ju-hyun -LRB- born June 28 , 1991 -RRB- , known professionally as Seohyun , is a South Korean singer and actress . She debuted as a member of girl group Girls ' Generation -LRB- and later its subgroup TTS -RRB- in August 2007 , who went on to be one of the best-selling artists in South Korea and one of South Korea 's most popular girl groups worldwide . Apart from her group 's activities , she has established herself as an actress , notably through her participation in the original and Korean versions of stage musicals including Moon Embracing the Sun , Gone with the Wind and Mamma Mia . She also starred in the drama `` Moon Lovers : Scarlet Heart Ryeo '' . She debuted as a solo artist with her debut mini album , Do n't Say No , on January 17 , 2017 , making her the third Girls ' Generation member to debut as a solo artist .