Boris with Michio Kurihara released their first collaborative album Rainbow on Pedal Records in 2006, with an international version following from Drag City.
While the album showcases the guitar work of Michio Kurihara, who is known as lead guitarist of White Heaven and The Stars, as well as for his support work for
Damon & Naomi, its sound offers a glimpse of a different side of both Boris and Michio Kurihara with a colorful selection of tracks that weave both parties together with synergy. After announcing Rainbow as Boris with Michio Kurihara, the band did a record release party in Tokyo then embarked upon a US tour. Rainbow remains a renowned best-seller to this day.