In April 2015, S.M. Entertainment announced that a personal study had been established for Lay's activities in China. In May 2015, he became a cast member of the Chinese program "Go Fighting!" In June 2015, Lay composed the song "Promise" for the re-release of EXO's second studio album, "Love Me Right". He also wrote the lyrics for the Chinese version of the song, while the Korean version was co-written by Chen and Chanyeol.