Sailor Quartet

The four are drawn as sisters close to Chibiusa in age, each one a counterpart and foil to a member of Sailor Moon's inner guard. Their names come from the earliest asteroids charted in the Solar System, Ceres, Pallas, Juno, and Vesta, bodies briefly ranked as planets after their discovery in the early 1800s.

Their ages even fall in the order those rocks were found, making Ceres the eldest and Vesta the youngest of the group.

The Quartet exist to guard their princess, Chibiusa, standing to her exactly as the inner Senshi stand to her mother, with Ceres leading them. When corrupted they became the sly, mischievous Amazoness Quartet, but their true nature is protective loyalty.

Once freed, they willingly returned to sleep rather than stay awake, content to wait for the day their princess would truly need them.

Long before their awakening, the Quartet lay dormant in the Amazon Jungle, waiting to shield Sailor Chibi Moon. Queen Nehellenia of the Dead Moon Circus dug them up too soon and twisted them into the Amazoness Quartet, the circus performers CereCere, PallaPalla, JunJun, and VesVes. In the Dream arc, Sailor Saturn sensed the buried Guardians inside them and tried to free them, but Zirconia locked them back into the Amazon Stones and seized them along with Chibi Moon and Saturn. After Nehelenia fell, Neo-Queen Serenity healed the stones at Saturn's request, releasing the four as true Senshi; they shared their story and returned to sleep.

The Stars arc pulls them back when Sailor Pluto detects a history-altering power and Chibiusa's transformation rouses them to follow her into the past. Finding their allies gone, they chased a great light to Sagittarius Zero Star, freeing Sailor Moon, Kakyuu, and Chibi Chibi from burning vines with Pink Ladies Freezing Kiss and clearing the threat with Amazoness Jungle Arrow. They stood by as Kakyuu dueled Phi and Chi, struck at Chi after the princess was mortally wounded, and threw themselves in front of Usagi when her own Guardians turned on her under the Galactica Bracelets.

Regaining their feet inside the ruined palace, they lent their strength to Sailor Moon above the Galaxy Cauldron, then heard the whole story from Sailor Cosmos before being sent home. The musicals rewrite them entirely as the Samael Quartet, girls fashioned by Professor Tomoe from Chibiusa's own Star Seed.