Takaya Aiba is the elder of the twins (for 30 minutes). He was saved by his father before he changes to a Radam Tekkaman and he escapes to defend Earth from their invasion. Aki and Noal find him when he fells to Earth and he claims he's lost his memories so they call him D-Boy. He can only remain in Tekkaman form for 30 minutes before he loses control of himself and becomes a killing machine. He knows he has to fight his siblings and close friends of him but he still desides to continue even if it pains him. He doesn't care whatever happens to him in order to save the planet.

In english version he is called: Nick Carter.