F.T. Island (Korean: 에프티 아일랜드, or FT아일랜드, Japanese: エフティー・アイランド; stylized as FTISLAND), also known as Five Treasure Island, is a five-member South Korean rock band formed by FNC Entertainment in 2007. The band consists of Choi Jong-hoon (leader, guitar, and keyboard), Lee Hong-gi (main vocals), Lee Jae-jin (bass and 2nd vocals), Song Seung-hyun (guitar, vocals, and rap), and Choi Min-hwan (drums and sub vocalist). Oh Won-bin left the group in 2009, and was replaced by Seung-hyun. They have one sub-unit, F.T. Triple (A3), consisting of Jong-hoon, Jae-jin and Min-hwan, but it has been inactive since 2012.
F.T. Island debuted in Korea on June 7, 2007, with the song, "Love Sick" on the music television program, M! Countdown. The band's Korean debut was successful; their debut album, titled Cheerful Sensibility was the sixth best-selling album in 2007. Their debut song "Lovesick" topped the K-Pop charts for eight consecutive weeks. Moreover, they also won the Best New Male Group in the Mnet Asian Music Awards and the Popularity and Newcomer Awards in the Golden Disk Awards in 2007.
The band then debuted in Japan a year later, on June 8, 2008, with the EP, Prologue of F.T. Island: Soyogi. However, it was met with limited success - it peaked at the 95th position in the Japanese charts and experienced sluggish album sales. It was not only until their third Japanese studio album, Five Treasure Island with the title track "Flower Rock", which made them as successful artists in Japan. The album achieved 1st position in chart ranking sales and sold more than 45,000 copies in Japan. They are also the first Foreign Male Band to top the Oricon Daily Charts, which is the first band to top it in 42 years.
In 2009, F.T. Triple was formed and they released their first single "Love Letter" in the same year. The band then promoted the single on various music programmes in Korea. F.T. Triple has also performed in F.T. Island's concerts such as Men's Stories in 2010, and sang the OST "Don't You Know" for the drama Master of Study. Main vocalist Hong-gi made his solo debut in both Korea and Japan with a mini album and a full album respectively. The Korean album was titled as FM302, and the album was released on November 18, 2015, while the Japanese album was titled as AM302, which was also released on December 9, 2015.
F.T. Island has released fifteen full-length albums, eight mini-albums, many singles and soundtrack productions for different drama theme songs and anime openings. F.T. Island is considered to be South Korea's first instrumental idol band. The band had also won various prestigious awards such as the Golden Disk Awards and Seoul Music Awards, and held more than 10 different tours since debut.