Princess Kaguya, the primary antagonist of the Kaguya Arc, originates as the Empress of the Moon ruling a race of bunny people. Over a millennium before the main events, she invaded Ancient Japan's Fire Country, demanding the Dragon Orb. Offered the Orb by a priest, she discarded it as worthless and pressed her invasion. The priest then used the Orb's power to become the original Ryuujin. Their battle concluded with Ryuujin severing Kaguya's rabbit ears, sealing her powers and forcing her into a thousand-year slumber. Her appearance shifts dramatically based on her condition. Initially, she appears as a fair-skinned woman with long hair, teal eyes, and a red forehead mark, wearing a distinctive fur-accented leotard, cape, and ruby-adorned boots. She hides her severed ears beneath a white rabbit headband. Without regular absorption of youthful energy, she deteriorates into a frail, elderly form with wrinkled skin and white hair. Absorbing sufficient youth—particularly from Sayaka Mine, descendant of the Dragon Maiden—restores her rabbit ears and triggers her transformation into her primal form: a massive, amorphous black blob with dark pink stripes, sporting ten rabbit-like hydra heads, beastly teeth, red eyes, and a distorted voice. Kaguya's survival depends on draining youthful essence from young women every 24 hours to maintain her beauty and power. Her abilities encompass energy manipulation, flight, hair manipulation, high-level regeneration, elemental control over earth, water, and lightning, weather manipulation, and fusion with other beings or objects. A critical weakness is her reliance on youth absorption; failure causes rapid aging and power loss. Sensing the Dragon Orb's energy in the present, she awakens and launches a second invasion using bamboo-shaped spaceships. Commanding four generals under Tsukikage, she threatens elimination for failure. Her primary objective is capturing Sayaka Mine, whose lineage is essential for restoring her full power. After confrontations—including petrifying rival Takeshi Onimaru and manipulating Tsukikage's brother Gekko—Kaguya absorbs Sayaka's youth. This restores her true form, enabling her to merge with her people and Earth itself. Yaiba ultimately seals her using Ryuujin's power. In the anime adaptation, this defeat returns her to slumber for another millennium. Later, during the Yamata no Orochi Arc, Kaguya reappears fused with Sayaka. Though reluctant, she collaborates with Yaiba to defeat Onimaru and the Yamata no Orochi. Following their victory, she and her people return to the Moon, aiming to restore it as a habitable world. The character draws loose inspiration from Kaguya-hime in *The Tale of the Bamboo Cutter*.