Energy

Energy is a non-physical substance present in humans that lets them sustain both physical and mental activity. Because it can be extracted and hoarded, it turns into a recurring target for the series' antagonists, who siphon it from people to advance schemes ranging from awakening a dormant power to keeping a monstrous tree alive.

Early on, harvested energy served the Dark Kingdom as raw fuel. One approach cast a wide net, striking gatherings where many people could be tapped at once, while a later method concentrated on a single person, feeding their obsessions until their vitality peaked and a monster could seize it whole. In nearly every case, once the creature responsible was destroyed, the stolen energy flowed back to those it had been taken from.

Other groups treated different reserves as energy. The aliens who brought the Makai Tree to Earth dispatched Cardians to gather it and keep the tree alive. The Death Busters prized pure hearts as an especially potent source, confirmed by Sailor Pluto, and one film reframed the idea as "Sugar Energy," the dream power squeezed from sleeping children.

Jadeite opened the Dark Kingdom's campaign, followed after his death by Nephrite, whose youma preyed on individual humans instead of crowds. Queen Beryl fed the accumulated energy to Metalia to stir her awakening, after which the kingdom abandoned energy gathering to chase the Silver Crystal. In the Crystal retelling, the Shitennou performed the same collection to rouse Queen Metalia.

Later threats followed suit. Ail and An sustained themselves and the Makai Tree through their Cardians, while Mistress 9 begged pure hearts from strangers to complete her rebirth inside Hotaru Tomoe, eventually consuming Sailor Chibi Moon's after Kaolinite delivered her. In the SuperS film, Queen Badiane sealed children in Dream Coffins to farm their dream energy and feed her Black Dream Hole.