Professor Tomoe was in his lab one day, and was showing some people (including his daughter Hotaru) his experiment. But something went wrong, and everybody in the lab was killed except for him. The Daimon Master came to Tomoe, and said if Tomoe would sell his soul to him, he would bring Hotaru back to life. Tomoe agreed.
Professor Tomoe became head of the Death Busters, and it was his job to find the talismans and get the Holy Grail. He must also help Mistress 9 summon the Master Pharaoh Ninety. When Neptune and Uranus summoned their talismans and defeated the Daimon Master inside of him, Tomoe became good again.
Mistress 9 possessed Hotaru, using Hotaru's energy for her own. Her only purpose was to summon the Master Pharaoh Ninety.
Mistress 9 was destroyed when Hotaru took over her own body.
Kaolinite was the first person to search for the talismans. She was seemingly killed when the inner scouts attacked her with Sailor Planet Power, and Uranus's "World Shaking" knocked her off the roof.
She appeared much later as a lab assistant to Professor Tomoe, and a tormentor to Hotaru. She was the one who stole Reeny's heart crystal, and fed it to Hotaru who turned into Mistress 9. While Tomoe congratulated her on finding such a pure heart, Mistress 9 let loose a blast that killed her.
Eudial took over after Kaolinite seemingly died. She had a special gun that when she shot someone their heart crystal would come out. She was also a very reckless driver ^_^. Of the Witches 5, she probably stuck around for the longest.
Eudial figured out that Uranus and Neptune had talismans sealed in their pure hearts, and took the talismans, but Pluto took them back from her and transformed the 2 talismans and her own into the Holy Grail.
Eudial took off in her car after that, but Mimete had rigged her brakes so Eudial drove off a cliff.
Mimete took over after Eudial was killed. She would find someone with a pure heart, then let the daimon swallow it and bring it back to the Professor. She usually went after people she had crushes on.
She tended to whine a lot, and would go after people with pure hearts who she liked (like idols, authors, etc.).
She was destroyed when she put herself in a machine to make herself stronger, but Tellu pulled the plug on her.
Tellu was associated with plants, and would use them to steal pure hearts from people. She didn't last long, however.
Viluy used computers and electronics to steal pure hearts. She also didn't last that long.
Cyprine took over after Viluy. She would capture a large amount of peoples heart crystals and bring them to the Professor. The Inner Scouts saw through their plans.
Ptilol appeared as Cyprine's twin. When they were battling the Inner Scouts, the scouts attacked them, and then Jupiter and Venus tricked them into turning their own attacks on each other, and they were destroyed