Question: Not Alone, is Zhang Liyin's which number overall single, Zhang held a showcase to support the release of the single, which was held at the Century Theater in Beijing, EXO members Tao and Chen were guests, Exois a South Korean-Chinese boy group based in Seoul? 
Sentence (from "Not Alone (Zhang Liyin song)"): Not Alone (我一个人) is Zhang Liyin's fourth overall single, released on August 20, 2014 in China and August 22 in South Korea.
Relevant evidence: Yes