Sailor Lethe

Sailor Lethe carries purple eyes, pale skin, and pink hair and lips against a green costume. Parted to the left with a downward curl in the right bang, her hair drops into four long spiral rolls, two per side, each gathered into a loose bun. An unconventional tiara crowns her forehead, where three strings of white beads suspend a purple gem with a small ornament and loop behind her head, and a many-pronged curved earring hangs at her left ear. A green choker circles her neck, centered on a white pointed star with a second ornament and purple stone dangling below. She wears a summer dress with straps, a pleated skirt, and a marked sailor collar, finished with thin-strapped green Grecian sandals and the Galactica bracelets.

Lethe's whole world is her twin. She guards Mnemosyne fiercely and will do anything to secure a calm, safe future for the two of them, treating her service to Galaxia purely as the means to that end. Beyond her sister she keeps no attachments, viewing other people as likely sources of grief. The larger war leaves her indifferent, and she does not care who prevails between Shadow Galactica and the Silver Millennium, only that the fighting stops.

Lethe and Mnemosyne originally protect the binary stars Lethe and Mnemosyne as true Guardians, unlike the false Animamates. Their homeworlds were already torn by war when Galaxia arrived and brought ruin, and with no way left to shield her sister, Lethe pledged herself to Shadow Galactica, taking up watch over the Desert River of Oblivion at Sagittarius Zero Star in hope of eventual peace.

When Sailor Moon, Sailor Chibi Chibi, Princess Kakyuu, and the Sailor Starlights pass through the Zero Star's gates into the desert, a hooded Lethe greets them in a boat and offers passage across the water. The crossing is a trap. She turns the sand to river and drops the travelers in, and her waters strip the memory from anyone who drinks. Usagi wakes at the riverbed, and Lethe tests her mind, judges her human memories worthless, and slays Luna, Artemis, and Diana before the amnesiac girl. She taunts Usagi and strikes with Galactica Myosotis Alpestris.

As Lethe readies her Galactica bracelets for the kill, Mnemosyne rushes in, embraces her, and pleads for her to stop, unwilling to watch her sister keep wounding them. She restores Kakyuu's memory while Usagi and Chibi Chibi recover theirs, and asks Lethe to let them through to Galaxia. Lethe resists, insisting the duty must be finished to earn their peace and calling the Silver Crystal a wellspring of war, until Usagi offers her own life to end the conflict. Mnemosyne waves them onward and Lethe relents, admitting the death would settle nothing. Moments later Sailor Phi and Sailor Chi descend on the river, brand the twins useless, and cut them down. The sisters hold each other as they crumble, and their Sailor Crystals are taken along with those of the still-incapacitated Starlights.