Sailor Stars musical, the bug theme was dropped. The Galactica Troops disguise themselves as Jūban Municipal High School students or as backup dancers for the Three Lights (depending on the musical) in order to observe the Sailor Guardians, and eventually attack them. The three of them engage a revived Queen Beryl in combat but are defeated by her, and subsequently killed by Galaxia for their failure. Sailor Chi has been portrayed on stage by Ado Endoh, Sachiko Akimoto, and Mari Yasuda. Sailor Phi has been portrayed by Kaori Ishikawa, Rieko Akimoto and Mika Komura. Sailor Theta has been played by Yūko Matsumoto, Ado Endoh, and Azusa Katagiri. Sailor Lethe and Sailor Mnemosyne and are twin sisters that appear only in the manga. Sailor Lethe is named for a naiad in Greek mythology, and for a river of the Greek underworld where dead souls go to forget their past lives before being reincarnated. Sailor Mnemosyne is named for the Titaness of memory, the mother of the muses, as well as another river in the underworld which brought remembrance and omniscience. Sailor Lethe has an attack called Galactica Myosotis Alpestris, which she used to attack Usagi. Myosotis alpestris is the name of an alpine species of Forget-me-not. They come from the conjoined twin planets Lethe and Mnemosyne, respectively. Their planets were small, poor, and plagued by violence and chaos. When Galaxia appeared and brought death and ruin, the two had no choice but to follow her in the hopes of someday finding peace. Sailor Lethe first introduces herself as the ferryman of the River of Oblivion, trapping Sailor Moon at the bottom. She kills Luna, Artemis, and Diana, and attacks Sailor Moon. She is stopped by Sailor Mnemosyne, who says that Sailor Moon has been hurt enough. Lethe says that Sailor Moon's Sailor Crystal is the cause for all of the wars they are experiencing, and that if it is destroyed, there will be peace. Sailor Moon offers her life if it will end the violence. Lethe and Mnemosyne are so moved by her self-sacrifice that they realize that whether or not Sailor Moon dies, the war will continue. Just as they are about to release the Guardians, Sailor Chi and Sailor Phi appear. They call Lethe and Mnemosyne useless fools and take their Sailor Crystals, which kills them. In the musical Le Mouvement Final, Lethe and Mnemosyne do not appear but