Sailor Senshi - Sailor Power Guardians

In the manga only, the Sailor Power Guardians look like sprites — tiny versions of the Guardian and Outer Sailor Senshi who live in their respective castles. The series shows only the Guardian and Outer Senshi as having Power Guardians, and although all eight are shown, only three of them are referred to by name: Guardian Uranus, Guardian Neptune and Guardian Pluto. The rest of their names appear in cast drawing in one of the artbooks. The Sailor Power Guardians are responsible for keeping the Castles safe while the Senshi are on Earth, and provide some of the Senshi with their Sailor Crystals during the Dream arc.

Each Power Guardian communicates with her respective Senshi by calling on the power of that Senshi's Sailor Crystal. The Power Guardians can help the Sailor Princesses call on the power of their Castles to produce a new transformation. Thus they upgraded to new forms and poured this power into the Rainbow Moon Chálice, which in turn allowed Usagi to become Eternal Sailor Moon for the first time.

The Sailor Power Guardians disappear in the Stars arc around the time of the killing of the Senshi they protect. The exact nature of their fate remains unclear, although the Senshi themselves later undergo rebirth.