Ayame Jinguuji serves as the director of the Supernatural Disaster Countermeasures Division, a government body operating under the Ministry of the Environment, during the events of Ga-Rei-Zero. She is the granddaughter of Fujiko Mine, who previously ran the agency and later returns to take over leadership following a critical incident. Physically, Ayame is confined to a wheelchair, though the tires are specifically enhanced for combat situations, and she is capable of equipping herself with a chain gun when necessary. She has brown hair and blue eyes, presenting the appearance of a young woman.

In terms of personality, Ayame is characterized as a kind-hearted and pleasant individual who carries a relaxed and gentle air about her. Despite her amiable nature, she is also a very serious person when the situation demands it, a quality that earns her the genuine respect of her subordinates. She demonstrates a unique, more personal touch by referring to spiritual beasts, most notably Ranguren, with affectionate nicknames that end in "-chan," such as calling the creature "Ran-chan".

Ayame's primary motivation stems from her duty as the head of the division, which involves making difficult decisions for the greater good. Her role in the story is central to the leadership of the organization that hunts supernatural threats. When the exorcist Yomi Isayama becomes corrupted and turns against the division, Ayame personally takes charge of the effort to stop her. She confronts Yomi directly, an act that leads to a fierce battle. During this fight, her personal assistant and close friend, Kiri Nikaidou, is forced to throw herself into the path of an attack meant for Ayame, resulting in Kiri sustaining critical, life-threatening injuries. Following this event, Ayame is presumed to have been killed, which directly prompts her grandmother, Fujiko Mine, to come out of retirement and resume command of the Ministry. However, it is later revealed in the final episode that Ayame survived the encounter and is seen recovering in a hospital, speaking with the now-wounded Kiri. After this incident, she eventually retires from active leadership of the division to care for her injured aide.

The most significant relationship in Ayame's life is with Kiri Nikaidou, her loyal personal assistant whom she affectionately calls "Kiri-chan". Kiri's sacrifice to save Ayame's life highlights the profound bond of loyalty and care between them. Another key relationship is with her grandmother, Fujiko Mine, whose return to leadership is a direct consequence of Ayame's apparent death. The narrative also hints at a deeper, tragic personal history. In one episode, Ayame is shown looking at a wedding ring and a photograph of herself from before she was confined to a wheelchair, in which she is holding onto a man whose face is not visible. During her confrontation with Yomi, she states that she once killed someone more important to her than anyone else, strongly implying that this husband may have succumbed to spiritual corruption, forcing her to destroy him just as she is now trying to stop Yomi.

Ayame's development throughout the story is marked by her transition from a capable and respected leader to a casualty of a tragic conflict, and finally to a survivor who steps away from her duty. Her abilities are not focused on traditional exorcist combat techniques, as her leadership and tactical command are her primary functions. However, when forced into direct confrontation, she is able to fight effectively from her wheelchair, which is equipped with enhancements, and can wield heavy weaponry such as a chain gun against powerful supernatural enemies.