The video below contains a series of scenes from kiotoshi, Onbashira’s famous log riding event in Shimosuwa. Parishioners sit on mammoth pillars and slide (or try to slide) down a none-too-gradual slope. This video from the 1992 festival is in Japanese, but the action speaks for itself. The main show starts about 1:15.
The video’s title reads: Onbashira! This is the real deal!