2009-10: Lineup changes, F.T. Triple and Breakthrough in Japon

On January 28, 2009, it was announced that member Oh Won Bin would indeed be leaving the group,[17] with FNC trainee Song Seung-hyun replacing him as a guitarist and backup vocalist.[18] With the new change in lineup, F.T. Island then released the music video for their mini-album with the title song, "Bad Woman".[19] They also promoted it on SBS Inkigayo, and two days later, released the band's first Korean mini-album Jump Up.[20][21]

On April 22, F.T. Island later released their second Japanese single, "I Believe Myself".[22] For the first time, members participated in lyrics composition. For the song "Moonlight Angel", member Jae-jin co-wrote the lyrics and leader Jong-hoon co-composed the song. "I Believe Myself" was the first Japanese single with member Seung-hyun.[23] They held their 2009 F.T. Island Tour-I Believe Myself in Osaka, Nagoya and Tokyo during the summer of 2009.[24] F.T. Island also toured parts of Asia which included Singapore, Japan, Thailand, Taiwan, and others to promote themselves in the summer of 2009. The showcase kicked off in Singapore during June 25 to 27.[25]

While preparing for overseas promotions, the members were in the midst of recording their third album. On July 9, FNC Entertainment released jacket photos for the upcoming third album called Cross & Change. On the following day, a music video teaser for "I Hope" was released online, featuring kids watching their idols (played by the members themselves) on TV. The title song, called “I Hope/Barae”, was released on July 16.[26] F.T. Island tried out a variety of music styles for Cross & Change; it included a total of 12 songs, ranging from moving ballads to addictive songs with a bright melody. F.T. Island adopted a new fashion style and concept for the album using a "retro" and the “Bokgo” approach, which was inspired during the “jeans jeans look” from the 80s in Korea.[27]

F.T. Island released their 3rd Japanese single, "Raining", on October 21. A music video of the single was released. Leader Jong-hoon played the piano for the single for the first time instead of the guitar.[28]

After celebrating their 1000th day in the music industry, they travelled to Japan and they stayed until the end of August to prepare for their major debut under their new Japanese label, Warner Music Japan. They also began a new Japanese television show which aired on April 7, 2010.[29] On May 19, F.T. Island released their new Japanese single "Flower Rock".[30] It entered the oricon daily charts in third position on May 19, 2010 on the day of its release, and held the fourth position of that week.[31] On July 14, F.T. Island released another single named "Brand-new days", which was written and composed by members Seung-hyun and Jong-hoon. F.T. Island performed a five-city concert tour in Japan after releasing both singles.[32][33] They also performed at the international rock festival Summer Sonic 2010 in Maishima Arena, Osaka, Japan.[34]

After promotions in Japan, F.T. Island focused on their comeback in Korea in mid-August.[35] Their new mini album Beautiful Journey and the music video for their main title song "Love Love Love" were released on August 25. They held their comeback performance in Korea on August 27. The title song topped many popular music charts in South Korea and also gained international notice, especially in Taiwan.[36] Jong-hoon co-wrote and co-composed the song, "Don Quixote's Song",[37] making it their first Korean song that includes the composition of a member. In November and December, F.T. Island held performances such as the Beautiful Journey Concert[38] and So Today... Concert tour,[39] in both Korea and Japan.

Whilst promoting their second Korean mini-album, F.T. Island recorded another Japanese single titled "So Today..." that was released in November. The song, "Boom Boom Boom", was composed by Jong-hoon.[40]The single ranked sixth on the Oricon Daily Charts. With F.T. Island’s 3rd single taking the sixth position, they then had a record of all their singles ranking in the top ten of the Oricon charts.[41] About 10,000 fans turned up at their promotional events in Osaka and Tokyo on 20 and 21 November.[42]

The band then held a concert in Taiwan on December 25, celebrating Christmas together with 9000 fans. Former vocalist and guitarist Oh Wonbin, appeared as a special guest and performed his first single as a solo artist and a brand new song, which had not been released at the concert. F.T. Island performed songs in three languages, Korean, Japanese, and Chinese.[43][44]

With an album sales record of over 100,000, F.T. Island won favorable comments in the Taiwanese media.[45] The revenue for concert tickets and merchandises alone and F.T. Island's Beautiful Journey concert had exceeded a total of NT$20Million.[citation needed] They have been named the Korean artists who earned the most money in the end of 2010.[citation needed] Four main news agencies namely, China Times, Yonhap News, Apple Daily and Liberty Times wrote news on the concerts, showing the band’s high popularity. F.T. Island also broke several records in Taiwan with 500,000 hits on mobile downloads and 10,000,000 hits on music downloads.[46]