|[List of appearances]|
When he was young, Kai and Nya's father was a blacksmith, and seen selling weapons door-to-door. At one point in his life, the First Spinjitzu Master granted him powers, and he became the first Elemental Master of Fire.
As a member of the Elemental Alliance, he fought to protect the people of Ninjago during the Serpentine Wars. At one point, with the Elemental Masters of Water, Light and Gravity, he attempted to defend a village from an Anacondrai attack led by General Arcturus, but the masters were defeated. However, the Elemental Alliance, led by Wu and Garmadon, sons of the First Spinjitzu Master, regrouped and fought against the Anacondrai army on an open battlefield. The Masters quickly gained the upper hand and had the Anacondrai on the run, until Chen intervened, and managed to turn the Elemental Masters against each other, with the Elemental Master of Earth attacking the other Masters. The Anacondrai then regrouped and won the battle. Later, when seeing a snake charmer, Garmadon realized that the Serpentine could be controlled with music. The Elemental Masters along with the sons of the First Spinjitzu Master used flutes to control the Serpentine and locked all of the Serpentine away in tombs except for the Anacondrai generals, who were banished to the Cursed Realm.
Later, in fear of his own demise, Sensei Wu made a map of the locations of the Four Golden Weapons and gave it to his friend. Kai's father later died and passed his blacksmith business to his son, who also inherited his elemental fire powers, while Nya got her water powers from her mother, Maya.
- Ninjago: Masters of Spinjitzu
- Pilot Episodes
- "Way of the Ninja" (mentioned only)
- Season 1
- "The Royal Blacksmiths" (mentioned only)
- Season 4
- "Spellbound" (flashback)
- Season 5
- Season 6
- Pilot Episodes