BUTOH MAY HAVE originated in Japan, but San Francisco is its American heartbeat. While in other places the dance form is a trend come and gone, here this strange language – with its mix of decadence, eroticism, and a compressed sense of time – continues to stir the imagination. Shinichi Momo Koga's six-year-old inkBoat travels between Europe, Japan, and the West Coast, absorbing influences and talents from all those places. Koga, who came to Butoh by way of film and theater, became hooked on the art through his studies and performing with Hiroko Tamano and Koichi Tamano. For his latest work, Ame to Ame (Candy and Rain), Koga is working with a new collaborator, drummer Sheila Denise McCarthy, who initially wanted to be an electronic engineer but became a composer. Another collaborator, Berlin-based Yuko Kaseki, is an extraordinary performer who was previously seen locally in last year's Onion. Producing a new full-evening piece each year, Koga is quite prolific; of Ame to Ame, he says that it challenges us "to walk on clouds, provoking the real topic: the return to earth." Not exactly the most decipherable description. But then that's Butoh for you. Fri.-Sat., 8 p.m., Yerba Buena Center for the Arts, 701 Mission, S.F. $13-$18. (415) 978-2787, www.ybca.org. (Rita Felciano)