Welvath was a female demon with long blonde hair, sharp teeth and a tentacle replacing her right eye, her arms split down the middle on each side and her breasts formed into faces with long forked tongues. She had small sharpened teeth in her maw, going nicely with her crooked grin.
Welvath didn't seem to have any special powers, but she had long claws which she could presumably use them for combat. The tentacled eyeball has potential to cause damage, and definitely looks freaky.
After Akira Fudo and Ryo Asuka are being attacked by the guests at the Black Sabbath held in Asuka's basement. One of them, a woman who is seen roaring in laughter at their beating, begins to transform into the horrific body-horror demoness that is Welvath. A tentacle pushes out of her eye, her arms split open down the middle and her breats tear open, eventually forming into the perverse body horror demoness Welvath.
Shortly after, Akira is combined with the spirit of Amon and forms into Devilman, he quickly ignites a slaughter by grabbing the head of the unsuspecting demoness, and crushing Welvath's head before tearing it from her body. Much to the horror and confusion of the surrounding demons.
- A T-shirt with Welvath's breast faces was released for the 40th anniversary of Devilman.
- Prithivi from the Megaten video games seems to be visually inspired by Welvath.
- Character designer and sculptor Yasushi Nirasawa designed a figure of Welvath that was put out as a part of the Fewture Models toy line. There were four variations of the figure put out, with the 'Glamours Trousers' version being limited to only 666 models.
- Another figure was advertised for the Marmit line, but ultimately never saw release. The packaging for the figures showed Welvath with a bright pink colour scheme, with blue hair.