These are the oni that are in charge of the afterlife for Chojin afterlife. They appear like traditional Japanese demons, who - neither good nor evil - keep the deceased chojin in line, by forcing them to work in order to earn a release from the afterlife. They encounter both Kinnikuman and Warsman during their service, as well as feature during the Survivor Match for the Kinniku Throne Arc.
Two Hakaba Oni introduce Kinnikuman to the Chojin Hakaba.  They reveal to him that he has died, and then command him to work in this version of afterlife, where it is seen that they supervise the forced labour camps. After Kinnikuman attempts his escape, they chase after him and are temporarily distracted by Warsman who attacks them.  Warsman eventually holds open the exit door for Kinnikuman, while the oni try to chase after him and fail. 
They state that people escaping is bad for their reputation, and attack Warsman for aiding in the escape.  Later, we see them watching Alexandria Meat's match against The Manriki on a small television set, where they cheerfully state that this competition will bring more souls to them.  One oni goes on to witness Doctor Bombe operating on Warsman, which causes him to attack.  They all notice Warsman then escaping, but - as he is no longer a corpse - they cannot stop his departure. They stand helpless, as he escapes from their afterlife.