Gensho (現象, "phenomenon") is the fourth collaborative studio album and seventh release by the Japanese rock band Boris and noise musician Merzbow. It is presented in two parts; the first disc features re-recordings of several Boris songs and a cover of the My Bloody Valentine song "Sometimes" in drone-based, drumless style, while the second disc consists of new compositions by Merzbow. They are intended to be played at the same time, much like the previous Boris double album Dronevil, or as separate works.