>>753808a big group of Japanese have an obsession with van darkholme and billy herrington, two gay porn actors
so they make these kind of humorous videos syncing them to pretty much anything
it has grown so big that Billy comes there and performs (not gay stuff) on stage for events and even their youtube (nico nico) convention
I found about gachi around 2010 or 11 because there was a ton of it on vinesauce autoplayer and I stayed for the quality