Oboro is the young leader of the Iga ninja clan and one of the central figures of the story. She is distinguished by a rare and dangerous inherited gift known as the Piercing Eyes, also called the eyes of destruction, a power that allows her to completely incapacitate an opponent with a single glance. Because of this ability, her eyes are regarded as the Iga clan's most potent weapon, and her role as heir to the clan leadership is closely tied to that power.

In temperament, Oboro is a gentle, kind, and selfless young woman. She is sweet-natured and somewhat naive, with a peaceful disposition that makes her reluctant to embrace violence. She tends to be passive, often accepting what happens around her rather than actively resisting it, but this passivity gives way to firm determination whenever the safety of other people is at stake. She cares deeply for her clan and its members, and she places great value on the preciousness of human life, a conviction that sets her apart from the ruthless warrior traditions of the ninja world she belongs to.

Her motivations are shaped by her love for Kouga Gennosuke, the leader of the rival Kouga clan, with whom she has secretly fallen in love. When the shogun Tokugawa Ieyasu deliberately reignites the centuries-old feud between the Iga and Kouga clans by ordering them to select five warriors each to fight to the death, Oboro and Gennosuke are designated as their respective clan leaders and are drawn into the conflict against their will. The two lovers initially try to prevent the meaningless and brutal contest by questioning the shogunate's motives, hoping to protect both their relationship and their people. As their comrades are killed one after another, however, they gradually come to accept their fate and the duties imposed on them.

Her relationship with Gennosuke is the emotional center of her journey. Their secret bond places them in an impossible position, forcing them to choose between love and loyalty to their clans. The death of Oboro's grandmother, the former Iga leader, alongside Gennosuke's father and Kouga leader Danjo, leaves the two young heirs to lead their warriors in the final confrontation between the clans. Throughout her development, Oboro moves from a passive, peace-loving young woman who hopes to avoid bloodshed into someone who must confront the full weight of leadership and sacrifice. In their last encounter, Gennosuke chooses not to defend himself and allows Oboro to strike him down, ending the fight with Iga declared the victor. In doing so, he entrusts her with a final mission: to save the ninja villages from the shogun's armies, which have been sent to exterminate both clans while their finest warriors are away.

Oboro fulfills this wish at great personal cost. She appears before Tokugawa Ieyasu and pleads with him to spare the villages, and as proof of her sincerity she blinds herself, destroying the source of her deadly power. Her act of self-sacrifice moves the shogun profoundly, and he withdraws his armies and issues an injunction protecting the ninja villages, allowing future generations of both clans to live in peace. In this way, Oboro's defining traits, her gentleness, her devotion to others, and her willingness to give up everything she holds dear, ultimately shape the story's resolution.