During the term of the Fourth Mizukage, Yagura, the Hidden Mist Village began the practice of pitting Academy graduates against each other in death matches as a final exam with the exceptionally skilled students named prime candidates for the Seven Ninja Swordsmen of the Mist. After Zabuza, not yet a student himself, killed over one hundred of his classmates, the practice was discontinued and he would thereafter be known as the "Demon of the Hidden Mist". His fame grew over the years as he became an Anbu, killing the Hidden Leaf Village ninja Kumade Toriichi at that time, before finally joining the Seven Swordsmen. At some point, he discovered Haku, a child with a special bloodline's abilities and began training him to be the ultimate weapon. In time, after his assassination attempt on the Fourth Mizukage in a coup d'etat failed, Zabuza subsequently fled with Haku and some other followers, such as the Demon Brothers, becoming mercenaries in order to gather funds for a second attempt in the future, which is why he worked with Gatō.
Expert Assassin: Knows the human body perfectly, meaning that he can easily kill most people in a single strike.
Jutsu: Special ninja techniques that utilize the user's Chakra as a source of power. Zabuza is an expert at using water-based Chakra.
Flying Revolving Sword Jutsu: Zabuza throws his blade and controls it in midair.
Hidden Mist Jutsu: Zabuza casts thick mist around him and uses it to disappear and confuse his foes.
Silent Killing Technique: Often used as a follow-up to the Hidden Mist Jutsu, it is a perfectly stealthy attack that is designed to catch the enemy off-guard.
Water Clone Technique: Zabuza creates several clones of himself out of water. These clones have 10% of his power, and they can't go to far from Zabuza.
Water Prison Technique: Zabuza traps the enemy in an inescapable bubble, where the victim is unable to breath.
Water Release: Great Waterfall Technique: This technique extends water over a large scale, surges and rises up to several dozens of metres high. Then it streams down to the ground in one big cascade, much like a gigantic waterfall. The wave destroys everything in its path.
Water Release: Water Bullet Technique: Zabuza expels a large quantity of water in the form of a powerful torrent towards their intended target.
Water Release: Water Dragon Bullet Technique: Zabuza shapes a large amount of water into a giant, powerful dragon, which hits the opponent with formidable might, dealing physical damage.
Demon Strike: With his chakra, strikes fear into his foe by giving them the sight of a demon.