Formed in the early '90s, when guitarist Wata, bassist/guitarist Takeshi, and drummer Atsuo met while attending a Tokyo art school, the Japanese experimentalists in Boris have traveled a bewildering path from their early roots as drone/doom merchants. Early efforts Absolute Ego and Amplifier Worship showed a deep debt to Bullhead-era Melvins, but Boris has ventured far afield since then. The band's 2005 breakout effort Pink introduced elements of shoegaze and dream pop into the stoner sludge template, while the following year's Rainbow explored more pastoral psych with guest guitarist Michio Kurihara. The prolific Boris went haywire in 2011, releasing three separate albums that leaped from J-pop to electronic dance music to accessible glam rock. This week the band takes the stage at the Rickshaw Stop for two nights, offering a career-spanning evening of classics Tuesday and a performance of its epic post-rock/sludge masterwork Flood Wednesday.