Himiko is the queen of Yamatai, a powerful country in the Eastern Planet that has inherited remnants of an ancient civilization. As its ruler, she possesses a unique and formidable power passed down through her ancestral line. Physically, she is a young girl of sixteen years, recognized by her long black hair with white streaks in her bangs, purple eyes, and two distinct purple dots on her forehead.

Her personality is a study in contrasts, blending the expectations of her royal station with the vulnerability of her age. She often comes across as selfish, arrogant, and willful, traits most evident in her relentless pursuit of Oda Nobunaga, whom she boldly declares to be her "husband-to-be" and attempts to bind to her through political arrangement. This behavior reveals a clever, determined, and somewhat calculating nature, as she skillfully navigates court politics to secure her engagement to the unpredictable young lord. Beneath this imperious exterior, however, lies a deeply caring and loving individual. Her affection for Nobunaga is genuine, rooted in a childhood memory of being playfully and kindly tossed about by him, a memory he himself does not share. This love ultimately proves to be her strongest motivation, driving her to acts of great courage and self-sacrifice.

Himiko's role in the story is primarily defined by her relationship with Nobunaga, placing her at the center of the series' emotional core and a developing love triangle. She is the catalyst for a key political alliance, bestowing upon Nobunaga a Regalia, a powerful artifact, which strengthens his campaign to unify the warring worlds. She quickly perceives that Jeanne d'Arc, introduced as a young man named Ranmaru, is actually a woman, making her the first to identify her as a direct romantic rival. Throughout the narrative, this rivalry creates significant tension, as Himiko fights not only for Nobunaga's political favor but for his genuine affection, a battle she ultimately recognizes she may lose as his bond with Jeanne deepens.

Her character undergoes a tragic but profound development from a seemingly self-serving queen to a martyr for a cause greater than her own desires. Early on, she appears as a manipulative figure using her power to ensnare a husband, but her commitment is proven when she physically jumps in front of Nobunaga to take a bullet meant for him, surviving the wound. As the war between the Eastern and Western planets escalates, she is forced to use her inherited power over the planet's Ley Lines to guide the great warship, Azuchi. This act comes at a devastating cost, as channeling such power leaves her terminally ill. She hides her fatal condition from Nobunaga, pleading with Leonardo da Vinci to keep her secret, which demonstrates both her strength and her fear of being a burden. In her final act, she disobeys Nobunaga's orders to rest, using the last of her strength to guide the Azuchi into the heart of King Arthur's castle, ensuring their victory. She succumbs to her illness in Nobunaga's arms, finally accepting his feelings for Jeanne and finding peace before her body returns to the Earth.

Her notable abilities are intrinsically linked to her role as the queen of Yamatai. She is a powerful priestess who can manipulate the mystical Ley Lines that run through the world, a skill that grants her immense influence over the planet's energy. This power, however, is not infinite and comes with a lethal drawback, as overexertion from using it to sustain the Azuchi's advance directly leads to her untimely death. Her possession of the Regalia also marks her as a key figure in the cosmic conflict, aligning her with the symbolic archetypes that drive the story forward.