On February 6, 2017, Soyou and Baekhyun were announced by Starship Entertainment to be collaborating on a duet titled "Rain".[3][4] The song reflects the melancholic feelings of nostalgia that accompanies the rain after a relationship comes to an end.[5] On February 9, a teaser video of the two singers recording the song was released.[6] On February 14, the song was released digitally accompanied by its music video. On February 15, Starship Entertainment released a behind-the-scenes video of the song's recording session.
The music video features a high school student (starred An Yu-jin, member of IVE) reminiscing on a rainy day by herself while listening to music.[5] It hit 1 million views in less than a day from its release. On February 15, Starship Entertainment released a special clip of the music video starring Soyou.
Upon release, "Rain" quickly reached the top on every South Korean online music charts, an achievement known as "all-kill".[7][8] The song debuted at number two on the South Korean Gaon Digital Chart.[9] The song placed first on QQ Music's K-pop chart as well as on YinYueTai's weekly music video chart.[10]
