Question: When was the South Korean singer, actor, host and entertainer born who was known as Ballad Prince and was also a star of Gu Family Book?
Sentence (from "Lee Seung-gi"): Lee Seung-gi (Hangul: 이승기 ; Hanja: 李昇基 ; born January 13, 1987) is a South Korean singer, actor, host and entertainer.
Relevant evidence: Yes