Kai Smith

Kai and his younger sister Nya worked as blacksmiths in the Four Weapons Blacksmith Shop for years until they met Master Wu shortly before Nya was kidnapped by the Skullkin Army. This leads Kai to learn Spinjitzu and train to become a Fire Ninja and successor of his father under Wu's guidance, in order to rescue his sister. After a successful training, he soon discovered his other teammates, Cole, Jay, and Zane, with whom he embarked on many adventures, battling the likes of the Skullkin and the Serpentine Army. After unlocking his true potential, Kai reflected his destiny of not becoming the Green Ninja himself after his days of training, but to protect and train Lloyd, who is destined to become one instead.

Kai has tall, thick spiky reddish-brown hair, shaped like fire. He is often seen with a focused expression on his face, with a scar visible on his right eyebrow and bandage above his left. Before Season 8, his eyebrows were black, his bangs parted to the right and instead of a scar, he had a notch on his left eyebrow. Kai wears Red Gi's All throughout the Series. Briefly that he will wear a different color. When he was a Blacksmith, Kai wore a white shirt and red pants as well as an orange apron.

Fittingly for his elemental affinity, Kai is a very hotheaded person, prone to taking action before thinking things through. He is capable of making careful observations when the need arises, but his emotions often override his caution. His single-mindedness made interaction with his teammates difficult at first (especially due to his worry about Nya and Cole), but he eventually learned to work with the other Ninja. He can be arrogant at times, insisting that he is better than his peers and growing depressed when he seems to be lagging behind their training.

Later, following the Ninjas' fame, Kai would end up getting something of a larger head and bigger ego, constantly flirting with girls and enjoying the merchandise styled after him. Likewise, he indulged in his fame the most out of all of the ninja.

Kai also has something of a stubborn side, believing that he is in the right until overwhelming evidence to the contrary is presented. This is especially pronounced during Lord Garmadon's stay on the Destiny's Bounty; Kai repeatedly accused the four-armed villain of treachery or plotting despite Garmadon's insistence that saving Lloyd was his primary concern at the time. On the other hand, Kai's stubborn streak lends him incredible determination that allows him to bolster the team's spirit in the face of impossible odds.

The most prevalent facet of Kai's personality is his good heart and dedication to people he cares about—if someone can earn his friendship, he will stop at nothing to protect them. Much of his stubbornness and recklessness are due to his desire to help his loved ones, either directly or by becoming strong enough to defeat anyone who might threaten them with their plans. In turn, his friends and family work to balance out Kai's more extreme traits, causing him to become a levelheaded mentor for Lloyd by the time he and his comrades begin training the Green Ninja.

He is tough, confident, his good heart and dedication to people he cares about—if someone can earn his friendship, he will stop at nothing to protect them. He did not like technology most likely due to his past upbringing but he has been seen playing video games and indulging in other technical items, meaning it has grown on him. He can rather be cocky, or thinks impulsively at some times, but he does acknowledge his mistakes through and through. He wasn't fully approved of Jay and his sister Nya's relationship at first, but as the series went on, Kai and Jay have shown themselves to good friends and work well as teammates.