Princess Kaguya is the name of the principle character in one of Japan's oldest tales called "Taketori-monogatari," otherwise known as "The Tale of the Bamboo Cutter." According to the tale, a bamboo cutter finds an infant, with the elegance of a princess, inside the stem of bamboo. He takes her home and she grows into a fine maiden who is admired by many. One day she tells the bamboo that she must return to the moon, a place that's her original home. She leaves and forever after, the bamboo is sacred.
This legend is included in the DVD extras.