[2] Later in the year, Hyun Young was diagnosed with a vocal cord polyp and underwent surgery for its removal.

[3] The group ended up not promoting together for a year and ten months in Korea, until this album.

[4] The album track list was revealed in a "Tracklist Video" featuring Woo-ri rapping the song titles in a cover of Azealia Banks' single "212".

[5] DSP confirmed on May 22, 2013 that the group would be returning after almost 4 months with the release of "Part 2" of the album on June 5, 2013.

The concept and style of the title track, "Sunshine" was described as "fun and colorful, and perfect for the summer season".