One never knows what to expect next from prolific Japanese avant-sludgmeisters Boris. The trio's propensity to change up its sound becomes even greater when the group collaborates with like-minded artists such as noise terrorist Merzbow or drone merchants Sunn 0))). For Rainbow — the group's 2006 album with Ghost/White Heaven guitarist Michio Kurihara that finally saw domestic release earlier this year — Boris straddles the line between face-melting guitar freakout and gentle psychedelia with hazy, ear-pleasing results. Opener "Raffelesia" recalls the epic shoegazer drone of "Farewell" from the Boris breakthrough Pink (minus that song's sheer riff tonnage), but the effort generally steers toward more concise songwriting. Though the krautrock pulse of "Starship Navigator" and the wailing "Sweet No. 1" offer a plenitude of corrosive guitar dueling between Kurihara and Wata, the material more often tempers the six-string squall with atmospheric melodies and restrained rhythms, as on "Shine" and "You Laughed Like A Water Mark." Fans of the galloping garage-punk fury featured on Pink shouldn't shy away from the quieter approach of Rainbow; Boris and Kurihara have joined forces for one of the most compelling recordings of both their illustrious careers.