She was ordered by Egos to hunt down the rat that has been revealing the society's secrets to Battle Fever. Death Mask accomplished this by disguising herself as a human and was also attempting to get the blue prints for Battle Fever's top secret robot. However the blue print that Battle Japan gave was a fake. And Battle Fever manage to defeat her at a scrap yard. Her main weapons are a cutlass sword and exploding daggers.
- Death Mask Monster's human form is played by the late Machiko Soga, who would go on to have several other roles in Super Sentai, such as Queen Hedrian in Denziman & Sun Vulcan and Witch Bandora in Zyuranger.