What are the red waves around fighters? In the anime Baki the Grappler, there are several scenes in the 1st and 2nd season when there is a bit of a staredown and these reddish waves emanate from their bodies when two characters are about to fight. 

What are these red waves?
After reading the manga, I have determined that this is the artist's way of depicting each fighter's aura or bloodlust.

It's not for a specific fighter or occasion and appears constantly throughout the anime and manga.