F.T. Island (Korean: 에프티 아일랜드), Five Treasure Island, or FTI, is a five-member South Korean band. The members are Choi Jong Hoon, Lee Hong Ki, Lee Jae Jin, Song Seung Hyun, and Choi Min Hwan. Their debut album, titled "Cheerful Sensibility", was the sixth best-selling album in 2007. Their debut song 'Lovesick' stayed on top of K-Pop charts for 8 consecutive weeks. The official fanclub name is "Primadonna" and the official fanclub color is sunshine yellow; the band's fans carry yellow flags known as "pentasticks".
Oh Won Bin had been a member of the band up until the beginning of 2009.
Although F.T. Island's first album, Cheerful Sensibility, was scheduled to be released commercially in May 2007, the members appeared on the show "Wanna be my boyfriend?" (Korean: 두근두근 여친만들기) on the Korean television channel MNet. The band also performed on stage live at Rolling Hall and held their first official showcase at Live House Melon-AX, Gwangjang-dong in Seoul on May 27, 2007.
On June 7, 2007 the group performed their debut song Love Sick on the music television program M!Countdown; their debut album, Cheerful Sensibility, was released on the same day.
Cheerful Sensibility combined 13 songs that were loosely divided into two parts, “Emotional Chapter” and “F.T. Island Chapter”, according to the genre of the songs. The “Emotional Chapter” consists of rock ballads. The "F.T. Island Chapter" was produced by the Japanese composers who worked with the Japanese band, SMAP and is composed of a variety of pop rock songs.