Sailor Mnemosyne

Pink runs through nearly all of Sailor Mnemosyne, from her eyes, hair, and lips to her clothing and shoes, set against pale skin. Parted to the right with an upward flick in the left bang, her hair forms four long spiral rolls, two on each side, each fastened with a bow of black thread. A nonstandard tiara sits at her brow, three strands of white beads holding a pink gem and small ornament that wrap behind her head, and a many-pieced curved earring hangs at her right ear. A pink choker encircles her neck, marked by a white pointed star with another ornament and pink stone hanging beneath. She wears a strapped summer dress with a pleated skirt and a distinct sailor collar, plus thin-strapped pink Grecian sandals and the Galactica bracelets.

Mnemosyne is tender and cannot stand violence, wishing only for a quiet, contented life at her sister's side. Lethe tries to keep her clear of the ugliest parts of their Galactica service, but watching her twin kill and maim finally becomes unbearable, and she intervenes even though doing so puts her own life on the line.

Mnemosyne and Lethe are the rightful Guardians of the binary stars Mnemosyne and Lethe, set apart from the counterfeit Animamates. Their worlds were already consumed by conflict when Galaxia came and dealt death, and left with few choices, Mnemosyne joined her sister in pledging service to Shadow Galactica, keeping watch over the Desert River of Memory at Sagittarius Zero Star while longing for peace.

When Sailor Moon, Sailor Chibi Chibi, Princess Kakyuu, and the Sailor Starlights reach the Zero Star, Lethe lures them into the Desert River of Oblivion, where they sink to the bottom and lose their memories to its power. The sisters' orders are to kill the intruders, and Lethe takes the task on herself so Mnemosyne can stay clear, leaving the gentler twin to watch from the bank. Mnemosyne looks on as Lethe cuts down Luna, Artemis, and Diana and attacks Usagi.

Just as Lethe moves to finish Usagi with her Galactica bracelets, Mnemosyne breaks in, wraps her sister in an embrace, and begs her to stop, refusing to watch further harm. She raises everyone out of the river onto the bank and uses the water of her own Desert River of Memory to return Kakyuu's memories, while Usagi and Chibi Chibi recover theirs unaided, and she urges Lethe to let them pass toward Galaxia. Lethe hesitates and argues that their duty must be met to win the peace they crave, until Usagi offers her life to stop the war. Mnemosyne sends them on and Lethe finally yields. Almost at once, Sailor Phi and Sailor Chi arrive above the river, dismiss the twins as useless, and strike them down. The sisters embrace as they dissolve, and their Sailor Crystals are seized along with those of the incapacitated Starlights.