zhāng yìxīng (hangul: 장이씽; hanja: 张艺兴; born in changsha on october 7, 1991) better known by his stage name lay (hangul: 레이) is a chinese rapper, singer, songwriter, dancer and actor. he became known after participating in a television program called "star academy" in 2005. he joined in exo on january 2012, as lead dancer, vocalist and visual member. in september of 2015, he published his autobiography, titled "standing firm at 24", beating records of book sold more in its pre-sale.