premise: Seohyun is only a director.
hypothesis: Do n't Say No is the debut extended play by South Korean singer Seohyun . Seo Ju-hyun ( born June 28 , 1991 ) , known professionally as Seohyun , is a South Korean singer and actress . She debuted as a member of girl group Girls ' Generation ( and later its subgroup TTS ) 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 . Seohyun ( born Seo Joo-hyun ) is a South Korean singer , member of Girls ' Generation and its subgroup Girls ' Generation-TTS .