Ruby Moon is one of two magical guardians that Eriol Hiiragizawa created, designed as a counterpart to Yue. Though technically genderless, Ruby Moon identifies as female. When Eriol transfers to Tomoeda Elementary, Ruby Moon takes on a human disguise as Nakuru Akizuki and enrolls at Seijou High School, landing in the same class as Toya Kinomoto and Yukito Tsukishiro—who is actually Yue in human form, unaware of his true nature.
As Akizuki, Ruby Moon becomes pretty much a constant nuisance. She makes it her mission to interfere whenever Toya tries to have a serious conversation with Yukito about his rapidly depleting energy. She claims she wants to drain Toya's energy for herself, though the actual motivation behind this never gets clearly explained. Once Toya finally manages to speak with Yue and transfers his magical energy to him, Ruby Moon loses interest and drops the act.
During the final confrontation, Ruby Moon faces off against Yue in combat. She seems to have the upper hand at first, but Yue ultimately overpowers her through sheer determination and his desire to protect Sakura.
In the Japanese anime, Ryoka Yuzuki provides her voice. The English dub, Cardcaptors, simplifies things by calling both her true and false forms Ruby Moon, with Willow Johnson handling the voice work.
Content compiled by AnimeList.moe from publicly available sources.
