Dr. Hajime Amami is a central figure in the narrative, serving as a distinguished scientist whose groundbreaking research inadvertently sets the story's events into motion. His background is rooted in the field of alternative energy, where he is on the verge of a major breakthrough concerning a new power source known as Rynax. He is a kind and intelligent man, whose dedication to his work is matched only by his deep affection for his daughter, Kurau. This caring nature is demonstrated early on when he fulfills a promise to bring young Kurau to his laboratory on the moon for her twelfth birthday.

The catastrophic experiment that follows defines his personality and motivations for the rest of the story. When an accident causes Rynax energy to strike his daughter, her body is inhabited by two sentient energy beings. This event leaves Dr. Amami wracked with immense guilt, as he holds himself responsible for the fundamental change his daughter has undergone. His primary motivation becomes a desperate search for a solution or a cure to reverse the effects of the accident and restore Kurau to what he believes is her original state. This guilt is compounded by his own physical damage, having been injured in the same incident that altered Kurau.

Despite his good intentions, Dr. Amami's role in the story becomes a tragic one. As the authorities, specifically the Global Police Organization (GPO), become aware of the Rynax's power, he is coerced into continuing his research on their behalf. He is forced to work on projects designed to capture or neutralize Rynax beings, which directly threatens his own daughter and her newly emerged Rynax pair, Christmas. This internal conflict places him in a painful position, torn between his duty as a scientist, his coercion by a powerful organization, and his love for his child. He attempts to atone for his past mistakes and protect Kurau from a distance, secretly hiring an agent named Doug to watch over and help her as she goes on the run.

Dr. Amami’s key relationship is, of course, with his daughter, Kurau. Their bond is complex and strained. While he deeply loves the daughter he raised, he struggles to fully accept the being she has become, which is a composite of her human self and the Rynax. He also has a relationship with the family housekeeper, Ella, a keen observer who understands the emotional rift between father and daughter better than they do themselves. Throughout the series, Dr. Amami undergoes a development born of suffering and helplessness. He transitions from a confident, leading researcher to a man broken by guilt, forced to work against his own morals, yet who still clings to the hope of saving his child, even if it means operating from the shadows. Regarding notable abilities, Dr. Amami possesses no superhuman powers. His significance comes entirely from his scientific genius in the field of Rynax research, which, ironically, becomes both a gift and a terrible curse for his family.