The Ninja was a great samurai who became an outlaw on charges of murder. Seeking to learn mystical powers as an apprentice of Master Khan he discovered the existence of K'un-Lun and decided to conquer the mystical city. During his assault, he was defeated by Lei Kung, and as his punishment, his spirit was bound to the book of many things, also known as the sacred volume of Kali by Yu-Ti.
The Ninja reappeared many years later assisting Iron Fist in infiltrating Harold Meachum's office building. When Iron Fist refused to kill Meachum out of pity, the Ninja appeared and killed Meachum himself. As it turned out, the Ninja had been taking possession of Lee Wing's body, who had found the book. When the book was destroyed, the Ninja was freed.