Myoga is a flea demon, Inuyasha's retainer, and the former guardian of Inuyasha's father's tomb. Four armed and the size of a regular flea, Myoga spends a considerable amount of his time being crushed or swatted. He resembles a bald old man with round eyes and droopy mustache, but with a carrot-like feeding tube instead of a mouth.
Being a flea demon, Myoga loves the taste of blood. In fact, most of his appearances start off with him sucking on Inuyasha until he's swatted off. Despite constant swatting, crushing, and flattening he appears to be indestructible to permanent physical harm. Despite being smushed paper thin, he's always back to normal after a few seconds.
That doesn't stop him from disappearing whenever there's trouble though. The minute there's even a hint of danger, Myoga either heads for the hills or gets behind whoever's the strongest fighter. Really though, his cowardice shouldn't surprise anyone. He's the size of a flea and he has no method to attack or defend. Why would he want to fight? His strength isn't fighting; it's information
Myoga knows everything, or at least seems too. Aside from being able to identify demons from the smallest clues and an extensive knowledge of lore, he seems to know everything that's going on in the Sengoku period. I guess he has some sort of information network with normal fleas who report to him. It's never really addressed that I'm aware of, but it would make sense.
The only other ability Myoga seems to have is that he can filter poisons and even harmful magic out of people by sucking their blood.
