An ordinary guy suddenly finds himself forced to fight a gladiator-like battle for a dark website that streams the violence for viewers. In order to survive and rescue his kidnapped ex-girlfriend, he must battle Nix, a heavily armed and much more experienced fighter.

Ninja Assassin follows Raizo, one of the deadliest assassins in the world. Taken from the streets as a child, he was transformed into a trained killer by the Ozunu Clan, a secret society whose very existence is considered a myth. But haunted by the merciless execution of his friend by the Clan, Raizo breaks free from them and vanishes. Now he waits, preparing to exact his revenge.