In 1985, Doctor Man and his army emerge to conquer but are met with opposition from five warriors chosen by the Bio Robo to defend the planet; the Biomen. Over the course of his battles with the Biomen, Doctor Man realizes that, in spite of cybernetic modifications, his health is failing him; leading him to desire to find a worthy heir to his empire. He first tries to accomplish this through creating an artificial "son" named Prince, modelling his appearance after what his son would look like as a 17 year old and naming Prince his second-in-command and successor. After Prince develops human emotions during an exchange with Ryuuta Nanbara and begins searching for his "mother" however, Doctor Man has Prince brought back to Neograd and reprograms him to be completely inhuman before sending him out to fight the Biomen, leading to his destruction.

Later, whilst watching TV Monster, Doctor Man notices a young man who resembles Prince participating in a live contest, causing Doctor Man to realize that is his son Shuichi. He sends Mason undercover with a squad of Mechaclones to bring him to Neograd but they are fought off by the Bioman. As such, Doctor Man disguises himself as a regular human and approachs Shuichi himself, revealing that he is his father. However, the Biomen and Shuichi later find out his father's identity as Doctor Man through a letter written by Shuichi's mother and a video recording of Kageyama's experiments. When Shuichi rejects Doctor Man's offer to rule with him, Doctor Man orders Mason to execute his son but the Biomen manage to fight him off. Doctor Man then converts himself into a full Mechahuman, dubbed "Neo Doctor Man", in order to get rid of his care for his son. The revelation that Doctor Man is a human leads Mason to conspire to overthrow him and to rope his fellow Big Three in on the plot. However, Doctor Man anticipates this and uses a body double to elude them before forcibly reprogramming all three of them to be completely loyal to him.