Shadow Galactica been played by two actresses, Haruko Yamaguchi and Megumi Wakamatsu. and appear only in Act 48 of 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
On the Transmigration of Souls this particular event." According to the composer, "Transmigration means 'the movement from one place to another' or 'the transition from one state of being to another.' But in this case I meant it to imply the movement of the soul from one state to another. And I don’t just mean the transition from living to dead, but also the change that takes place within the souls of those that stay behind, of those who suffer pain and loss and then themselves come away from that experience." The work is scored for an SATB chorus, a children's choir, and an orchestra