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. It remained on the Oricon indie chart for seven consecutive weeks and also hit an impressive No.