Yaiba Kamikaze used to be part of a ninja clan that put its ninjas through a test where they had to fight against highly skilled members of their clan - basically, they had to fight Yaiba. Yaiba grew tired of his clan so he slaughtered them all and left them for dead. Yaiba eventually runs into Ryu Hayabusa and challenges him. Ryu cuts off Yaiba's left arm and eye. Yaiba is later found by an organization that replaces his missing body parts with cyborg enhancements. Around this time, a zombie outbreak has happened and Ryu Hayabusa is trying to stop it. Yaiba is ordered to stop the outbreak as well, but his real goal is to exact his revenge on Ryu Hayabusa for defeating him.
Yaiba: Ninja Gaiden Z is a third person hack and slash action game that plays similar to the rest of the Ninja Gaiden series. Players take control of Yaiba and fight off enemies with his sword and cyborg enhancements. Emphasis is placed on slaughtering your opponents to build up the bloodlust meter that allows Yaiba to kill multiple enemies quickly.