In the manga and Crystal series, the Death Busters use a power source called the Taioron Crystal which is the life source of their homeworld. One fragment somehow ended up in the possession of Hotaru's late mother, Keiko Tomoe, with Professor Tomoe giving the item to Hotaru in order to ease her seizures while nourishing Mistress 9 until the Daimon stole Chibiusa's Legendary Silver Crystal. The Saturn Crystal is her Sailor Crystal and the source of all her power, which becomes especially important in the fourth and fifth sagas.