While working with the band, frontman Jung Yong-hwa was cast in the television drama You're Beautiful (2009), where he first garnered recognition.

After being scouted by FNC Music's casting director, Jung Yong-hwa, Lee Jong-hyun, and Kang Min-hyuk met while auditioning for the agency.

[1] In late September, bassist Kwon Kwang-jin left the band due to "personal reasons" and was replaced by Lee Jung-shin later that year.

[1][5] During this time period, Jung was cast in Seoul Broadcasting System's (SBS) television series You're Beautiful,[6] where he played guitarist Kang Shin-woo in the fictional band A.N.Jell.

[11] In addition to video teasers, each member was accompanied by a word that made up the acronym BLUE, which was meant to portray their individual images.

[14] The fourth and final teaser featuring Jung with the word "emotional" was revealed one day prior to the release of the mini-album.

[23] Performing only in Japan up to its debut, CNBLUE also sought to execute a series of guerrilla concerts in South Korea.

The first performance was decided by guitarist Lee; dubbed the "Burning Street Concert", it took place in Hongdae, Seoul.

[26] By the end of the year, the mini-album sold 77,183 copies and was ranked at the 12th best-selling album in South Korea.