Maria is the sister of Tomisaburou Tengai and the recognized reincarnation of the Virgin Mary. This divine status designates her as the primary target for the 13 Doctors, also known as Apostles, who require her unique blood for experiments aimed at reviving their god. Her distinct biological properties are fundamental to their scheme of creating a new deity.

Maria meets her end in Shinichi Kuruma's arms during the original series. Her death directly ignites the "Great Destruction," a devastating chain of earthquakes that ravages Shinjuku. Following her demise, Shinichi consumes Maria's corpse to absorb her essence and powers, integrating her abilities into himself. This act forges an irrevocable biological and psychic link between them as her cells become part of his physiology.

In the sequel *Beast Fighter: The Apocalypse*, Maria's legacy pulses through the narrative. Her blood, isolated from Shinichi's system, is utilized by Dr. Genzou Kuruma to create clones of a godlike entity named Noah. These clones manifest a third eye and wield divine powers, with one embodying benevolence and another wrathful judgment. Her genetic material remains a coveted element for antagonist experiments, highlighting her enduring significance to the series mythos beyond death.

Her relationship with Shinichi and the manner of her death profoundly haunt his character development as he contends with the consequences of harboring her essence. The psychic connection established through her integrated cells also functions as a plot mechanism driving specific character interactions and conflicts in the sequel.