Hisayo Otsutsuki, who was born Hisayo Tsukino, was believed to be a normal second-year middle school girl, who happened to be a Kunoichi, whose own life changes one day when she and her sister, Usagi Tsukino, meet a black and dirty blonde cats. The cats name are Luna, who bears a crescent moon mark on her forehead, and Phoebe, who bears a gold dot in the middle of gold circle on her own forehead, both can talk. Luna and Phoebe tell Usagi and Hisayo that they are the Chosen Guardians of Justice with the power to transformer into Sailor Moon and Sailor Sun. Usagi and Hisayo now have a new responsibility which is a mission to find the Illusionary Silver and Ruby Crystals as well as the other Chosen Guardians to protect the Moon and Sun Princesses. During their mission, they must deal with the various enemies, who is also after the Illusionary Silver and Ruby Crystals.
After being sealed, instead of finding herself trapped in the moon again, Kaguya found herself in another world in the body of a young girl who seemed to have just been turned into a demon based on the people around her. As she lives life with the name Nezuko, she begins to regain her old features, such as her hair and eyes. Now she must learn to conquer the sun, as ironic as it is when she was sealed into the moon, and become one with her new brother again.