The group's base was created in 1993 when brothers Kōshi (elder: vocals) and Take (younger: guitar) began playing together. They formed Flow in 1998, and were eventually joined by Keigo (vocals), Gotō (bass) and Iwasaki (drums; joined in 2000). In 2001, the band released its first maxi single, "Flow #0". The group then released two mini-albums within the same year, both of which took nationwide indie charts by storm. "Okuru Kotoba", Flow's first cover single, was released in January 2003.