Reincarnated from a turtle formerly belonging to Gorō Mutsumi, Ayumi was born on November 20, 1984, and adopted under that name. During a harsh winter, Gorō noticed her attempting to hibernate and dug her a shelter near a ginkgo tree in a park. A girl sharing her name assisted them in securing the turtle’s hibernation. When spring arrived, the park’s demolition destroyed the ginkgo tree, crushing her to death. This event ingrained persistent fears of darkness and confined spaces in her guardian angel form.

As a Senior-ranked guardian angel with black as her image color, she wears a green beret-like hat symbolizing her turtle shell. Her personality involves deliberate decision-making, often appearing slow due to meticulous forethought. She habitually scolds others, particularly Mika, reflecting a historic turtle-rabbit rivalry. Among the twelve guardian angels, she is Shin the Black Turtle’s designated bride and reciprocates his feelings more intensely than other angels abducted by the Saint Beasts.

A shared fondness for drawing connects her to the original human Ayumi, evidenced by sketches from both. Her role later expands as she is identified among the chosen brides for the Four Saint Beasts.