Question: When is the cast in The Guardians born that is a South Korean singer, actor, fashion designer and television presenter?
Related documents: [0]  [DOC] Kim Ki-bum (born September 23, 1991), better known by his stage name Key, is a South Korean singer, actor, fashion designer and television presenter. Born and raised in Daegu, South Korea, he later travelled to Seoul after a successful audition at the S.M. National Tour Audition Casting. In 2008, Key debuted as a member of South Korean boy group Shinee, who later went on to become one of the best-selling artists in Korea. Key is widely recognised as a singer, but he has also ventured into different careers, notably as an actor and fashion designer. [END] 
[1]  [DOC] The Guardians (Hangul: 파수꾼 ; RR: "Pasuggun "; lit. Lookout ) is a South Korean television series starring Lee Si-young, Kim Young-kwang, Kim Tae-hoon, Kim Seul-gi and Key. The drama aired on MBC on Mondays and Tuesdays at 22:00 (KST) from May 22 to July 11, 2017. [END] 
Answer: 
September 23, 1991
September 23, 1991