Kumo-otoko

One of the original eight demons who closely supported the Fuujin oni, reincarnated in the body of a spider and thus took the shape of his host.
Prefers to fight using head over brawns... but fails miserably at it: even though he is smart enough to create complex plans that actually work, his goofy nature causes them to backfire humorously most of the time.

He becomes Onimaru's right hand man, not because of his merits but because there was nothing better at the time. He is constantly sent to do his master's bidding, such as recruiting new warriors or gathering intel.

Even though he is part of Onimaru's ranks, he is actually not a bad guy. However, his undying loyalty towards his master is evident, but he never shows any real ill-will towards Yaiba's group. This trait also causes him to be the only one of the eight demons to back up Onimaru until the very end (the others either were slain, or changed sides), even though he is mistreated quite often.