What are the origins of the Witches 5 ?

[Kunzite]

It is interesting to think about.

[Outer Sailor]

In the Manga they are implied to have been created by Tomoe artificially. No explanation is ever given in the original anime. Crystal follows the manga. PGSM didn't get that far.

[PRangerX]

I'd actually envision the Witches given up there pure hearts to become Death Busters. At least in the anime. It would be interesting for a back story.

[Goldar's Revenge]

Manga Tomoe could have used the bodies of previous victim's to make the Witches too.