Summary
Guardian Cosmos serves as the enigmatic guardian spirit of the Cosmos Crystal, residing within the Galaxy Cauldron. She makes a singular appearance in the very final chapter of the manga. Standing as one of the most mysterious figures in the entire Sailor Moon series, she appears to be the Sailor Power Guardian for the Cosmos Crystal, Sailor Cosmos, and by extension, Usagi herself, though this connection is only implied rather than explicitly stated. The narrative suggests this role is made possible through a deep link involving herself, Queen Serenity, and the ancient birth of Princess Serenity, yet the specific events that transpired between them remain open to interpretation.
