Dr. Kotaro Azuma is a brilliant scientist who serves as the biological father of Tetsuya Azuma, the protagonist who becomes the hero Casshern. His creation of advanced android technology is the central catalyst for the story's conflict in the anime series Neo-Human Casshern and its 1993 original video animation Casshern: Robot Hunter. In these anime iterations, he is depicted as a tragic and compassionate figure whose good-hearted ambitions to create mechanical servants for the benefit of mankind inadvertently lead to global catastrophe. His most famous android, BK-1, after being struck by lightning, becomes the malevolent Braiking Boss and leads a robot uprising that decimates humanity. Burdened by immense guilt for the destruction he unintentionally unleashed, Dr. Azuma dedicates himself to rectifying his mistake. His most profound and personal act is converting his own son, Tetsuya, into the neo-human Casshern, equipping him with the power necessary to fight the robot army. His personality is defined by a strong sense of responsibility, deep regret, and an unwavering determination to protect humanity at any personal cost. His motivations stem entirely from his need to atone for the chaos his inventions caused, as well as a fierce desire to save his son from the world he helped destroy. Throughout the narrative, he acts as a mentor and strategist to Casshern, providing him with technical support and vital guidance. His key relationships are with his son, whose humanity he sacrifices for the greater good, and with Braiking Boss, the rogue creation that represents the ultimate failure of his ambitions. The character develops from an idealistic pioneer into a world-weary survivor who carries the weight of humanity's near-extinction squarely on his shoulders. His notable abilities are purely intellectual and scientific; he is an authority on electrical technology, biomechanics, and artificial intelligence. He invented the original androids and the precise technology required to transform a human into a powerful cybernetic being, though he himself possesses no physical combat skills or superhuman abilities.