Tetsuya Azuma, also known as Casshern, is an android with a human consciousness neoroider. Tetsuya turned himself into an android for the purpose of hunting down and destroying robots that have taken over the world. His biological father, Dr. Kotaro Azuma, was the inventor of the automatons that were originally intended to serve humankind. However, the first android, BK-1, was struck by lightning, and went out of control.