Midori Isami is a central figure in the anime Brain Powerd, primarily defined by her role as a scientist dedicated to the mysterious alien spacecraft known as Orphan. She is a woman in her early forties, specifically forty-two years old, with brown hair often styled in a bun and blue eyes behind her glasses. As the wife of fellow researcher Kensaku Isami, she is also the mother of two children, Yuu and Iiko Isami. Her professional dedication is immense, as she has poured her life into the study of the Organic Engine and the power of Orphan, a commitment so consuming that she and her husband left their young children in the care of their grandparents to focus entirely on their work.

Driven by an ambition that borders on obsession, Midori is portrayed as a woman who lives for her research with the goal of obtaining power and harnessing organic energy, aspiring to become a leading authority within the Orphan project. Her personality is marked by a cold and calculating demeanor, often appearing emotionally detached from her family. This is most starkly illustrated by her open affair with Jonathan Glenn, a much younger Gran Cher pilot in her command who is also a sworn enemy of her son. These scenes highlight her commanding and controlling nature, suggesting she is the one in charge in all aspects of her life, including her intimate relationships. Her ambition and personal choices create a deep rift within her family, placing her in direct opposition to her son Yuu, who ultimately abandons Orphan after learning of the catastrophic consequences of his parents' plans.

Within the story's conflict, Midori serves as a high-ranking antagonist. She and her husband work within Orphan to unlock its vast knowledge, aiming to raise the ancient vessel to the surface and travel the galaxy, an act that would result in the annihilation of all life on Earth. Her role is that of a dedicated scientist on the Reclaimer side, leading the Grand Cher army in its mission to retrieve Orphan's vital disc plates. Her key relationships are complex and fraught with tension. With her husband Kensaku, she shares a professional partnership in their scientific ambitions. With her son Yuu and daughter Iiko, her relationship is strained by years of neglect and her personal betrayals, creating a family split by the central conflict of the series. Her relationship with the young pilot Jonathan is a significant part of her character, explored with explicit tension that further complicates the family drama. Notably, Midori Isami exhibits little emotional development throughout the series, remaining largely fixed in her coldly ambitious pursuit of power and scientific discovery, a steadfast obstacle to the protagonists. Her notable abilities are rooted in her intellect and scientific expertise, making her a formidable leader and researcher in the field of organic mecha technology, a position that earns her the formal title of Dr. Isami.