Who is the true moon princess in Sailor Moon?

The true Moon Princess in Sailor Moon is indeed Sailor Moon herself. Initially known as Usagi Tsukino, she discovers her true identity as Princess Serenity, the reborn princess of the Moon Kingdom, during her battles against various enemies. As the Moon Princess, she possesses the Silver Crystal, the most powerful artifact in the Sailor Moon universe, and holds the destiny of the Moon Kingdom and the entire solar system in her hands. With her unwavering determination, love for her friends, and the ability to transform into Sailor Moon, she fulfills her role as the true Moon Princess and the guardian of the Earth.