Written by Han Seong-ho and Amen, the funk-rock track was released under FNC Music on January 14, 2010.
Unprecedented at the time, CNBLUE held the record for shortest period between debuting and earning a music show win for four and a half years.
The composers Kim Do-hoon and Lee Sang-ho faced a lawsuit filed by indie rock band Ynot?
[3] Writing for Newsen, reporter Cha Yeon described the track as a "modern funk-rock song" with an "addictive" and "strong" melody.
She noted that the guitar riffs and chord progression produced a "refined charm", which offered an alternative to the hook songs of other idol groups at the time.
[7] CNBLUE won the Mutizen Song award on Inkigayo two days later, the band's second and final win.
[21] Musical theatre actor Kang Dong-ho covered the song, which was re-titled to "I'm a Loner (A Train to the World)", on the March 6, 2016 episode of King of Mask Singer.