Yamabushi were Japanese mountain ascetics and warriors, mostly of the Shingon sect of Buddhism. For the most part solitary, they did form loose confederations, and associations with certain temples, and also participated in battles and skirmishes alongside samurai and sohei on occasion.
Yeah, these guys are pretty awesome. Ninjas are officially out, yamabushi are in. I mean, just look at that guy. He's got the headgear. He's got the sword. He's got the spear thing. He's got the sandals. And, he's got the "you're ass is mine" point down. Ya, yamabushi.