Rainbow is a collaborative album between Japanese rock band Boris and guitarist Michio Kurihara.

Wata contributed vocals to the title song, which has a music video made for it by Foodunited.

Drag City released this album in the United States on May 15, 2007 with a different 9th track, on CD format only.

In 2007, the album was also released on vinyl in two forms by Inoxia Records: an unlimited LP which contains the album (same as Pedal CD version), and a double LP box set with a 50-page photo book in a special cover, the album on clear vinyl, a second LP containing two bonus ambient tracks (also on clear vinyl), and a DVD featuring the music video for "Rainbow".

The title track on the 2xLP version features an alternate mix with a different guitar solo, and re-recorded studio takes were used on Boris / Variations + Live in Japan and Gensho.