Imahori began to play acoustic guitar at age 12, inspired by British folk music from the likes of Bert Jansch and the work of Frank Zappa and Andy Partridge.

In 1986 he formed the band Tipographica, with saxophonist Naruyoshi Kikuchi and jazz pianist Akira Minakami.

After providing the soundtrack to Gungrave for PlayStation 2 in 2002, the concept was subsequently developed into an anime series, also scored by Imahori.

He is perhaps best known in the US as the composer of several anime soundtracks, primarily Trigun, Gungrave and Hajime no Ippo, though he has also contributed tracks to Texhnolyze, Wolf's Rain, and Cowboy Bebop.

Imahori has worked with Yoshida Tatsuya of Ruins fame, and also with Yoko Kanno as a member of Seatbelts.