Kai

''"Don't forget we're ninja." ''-Kai

Kai is the Red Ninja of Fire. His sister is Nya (who is also Samurai X). He was chosen to protect the Green Ninja (Lloyd Garmadon) along with the other three Ninjas. He is the only character known to have a sibling, and he was the final ninja to unlock his true potential.

Early Life
Kai, along with his sister, were the children of the blacksmith and owner of Four Weapons. When their father died, Kai took it upon himself to keep the family business going and swore he would become an even greater blacksmith than his father.

Way of the Ninja
When the Four Weapons Blacksmith shop was attacked by Samukai and his Skeleton army, Kai attempted to defend it with some samurai armor he made. The armor was slow and clunky however, and he was soon subdued, and would have died were it not for the quick action of Sensei Wu. Wu then told Kai about The First Master of Spinjitzu and his two sons who fought over the four Golden Weapons, explaining that a Honest Man had been entrusted with the map to their resting places and the honest man was he's father. Sensei Wu took Kai to the Mountains of Impossible Height in order to train him to be a Spinjitzu master so he could save his sister, and all of Ninjago. During his training, Kai had to learn patience and how to harness the "fire" inside of him. This training consisted of running a course before Sensei Wu finished his tea. Kai accomplished this after several days by knocking the teacup out of Sensei's hands when he was about halfway through the course with his wooden training sword. He then told Kai to get some rest, and that his final test would come in the morning.

The Golden Weapon
Later that night, while Kai was pondering Sensei Wu's training and brushing his teeth, he was set upon by three black-suited ninjas. Kai was able to fend them off for a while, disorienting them on the training course. Before they could fight much longer, however, Sensei Wu arrived and told them all to stop, at which the three ninjas revealed themselves as more of Wu's students. Wu used Creation to give each of the ninjas a suit that matched their elemental properties, and introduced them to each other. He then told them what they needed to do to defeat Lord Garmadon, who is Wu's brother. Cole interjected and asked if they were still to learn Spinjitzu first. Sensei then informed them that they each already knew it, but it must be unlocked at the right time. Then Wu said that they would take the horse carriage (pulled by Kai and his fellow Ninja) to the Caves of Despair, the location of the first Golden Weapon, The Scythe of Quakes. At the Caves of Despair, Kai ran ahead of the other ninjas while Cole was formulating a plan. The other three ninjas chased after him, and caught up to him just before the chamber where the Scythe was housed. Jay then accidentally revealed their position to the skeleton army digging for the weapon, and they were soon in a battle. After Jay discovered the key to unlocking his Spinjitzu, Kai and the others were quick to follow. They used it to drive off the skeleton army, after which they discovered that they had bigger problems, namely, the weapon's guardian, the Earth Dragon. Kai happened to be holding the Scythe at the time, and decided that the only way out was to use it, contrary to Sensei's instructions. After escaping, Kai was strictly repremanded by Sensei Wu, and they went onward toward the next weapon, The Shurikens of Ice.

King of Shadows
While on their way to the Frozen Wasteland, the location of the Shurikens, Wu told the ninjas about the most powerful technique in Spinjitzu, the Tornado of Creation. Kai began to attempt it, but was stopped by Wu, who explained that it could have disastrous concequences if done incorrectly. When the ninjas arrived at the location, they discovered several skeleton warriors frozen in ice, and deduced that they had been the second people to get there. When they discovered the Shurikens suspended from the celing, they lifted Zane up to grab them. When he did, a block of ice formed around him, and the Ice Dragon awoke. The ninjas then used Zane as a sled to escape, and went to the hiding place of the Nunchucks of Lightning, the Floating Ruins. On top of the chain, Jay found the Nunchucks, as well as the Lightning Dragon. As they were being chased by skeletons, the ninjas used Jay's wing-glider invention to leap off the chain and get away to the Forest of Tranquility. While they were sleeping that night, Kai thought he saw his sister Nya. He got up and chased her to the Fire Temple, where he discovered that it wasn't really Nya, but a shadow deception created by Lord Garmadon. His sister was in the Fire Temple however, only suspended over a pit of lava. Kai had to remove the Sword of Fire from its pedestal to cut the chain and save his sister, which was Garmadon's plan all along. He cintrolled Kai's shadow, and used it to defeat him. The shadow couldn't be hurt by Kai, but Kai could be hurt by the shadow. Garmadon made multiple copies of the shadow, which made quick work of Kai, and obtained the Sword. All would have been lost if Sensei Wu hadn't intervened at that moment, using his own shadow to defeat Garmadon's Shadow Warriors, regaining the Sword. Garmadon then decided to awaken the Fire Dragon, knowing the guardian would impede the band. The dragon blocked the entrance to the temple, which meant it would be easy for Garmadon to bring the other three weapons to the temple and unite them there, as Samukai had ambushed the other ninjas. Wu then sacrificed himself to go to The Underworld, in order to keep the weapons apart.

Weapons of Destiny
Kai and Nya discovered that the Dragon only wanted to protect the Sword, and the ninjas used the guardians to go to the Underworld to help Sensei Wu. The Dragons preformed their variation of Spinjitzu and crossed over, landing not far awat from the Skulkin Fortress. They tried to make their way overhead by grabbing onto the roots of plants only to discover that they were spider legs. Out of fear they dropped down to the floor below, where they were noticed by Nuckal. They were going to defeat the Skulkin until the Spiders landed on the stone surface also. Thinking fast Jay remembered the Tornado of Creation. And although Zane protested about disatrous concequences, they used the Tornado, successfully defeating they're enemies. They arrived in the fortress to witness Sensei Wu being defeated by Samukai. Samukai acquired all of the Golden Weapons once but in doing so destroyed his body and transformed him into a portal which Lord Garmadon quickly escaped through. Sensei Wu assured him about Lord Garmadon and the ninjas departed the Underworld. Kai and his new friends went back to the Blacksmith shop and were greeted by Nya and several villagers.

Flight of the Dragon Ninja
Cole, Zane, Jay, and Kai were told to by Sensei to train but, instead decided to hold a Dragon race. Zane felt that they should be training but, Kai told him riding your dragon "was kinda training." Kai and the other ninjas raced for a while but Cole won when he "activated the turbo" by throwing food in front of his Dragon's nose. Although he won Kai said that they'd get him the next day.

The New Masters of Spinjitzu
While Kai and the others were sleeping Nuckal and Kruncha stole his sword in hopes of preforming Spinjitzu. They turned on each other though and while they were fighting Kai came out half-asleep and walked by the still pair and turned of the training course that they activated. Believing that the training course turned itself on, Kai yelled to Jay to fix it, but Jay said that he'd "do it tommorow." When Kai was back asleep the two Skulkin put the weapons back in their places since they couldn't control them.

Return to the Fire Temple
The Fire Dragon, Flame flew Kai and Nya to the Fire Temple, wanting to show them something. After dismounting Flame led Kai to a passage connecting Ninjago to the Underworld. Kai started planning what to do when the ground fell out from beneath him. Krazi noticed him and alerted Wyplash, who sent several Skulkin after him. He dissarmed his enemies, but they picked him up. Nya and Flame then shot a blast of heat scaring the Skulkin and sealing the passage.

Rise of the Snakes
When reports of Lord Garmadon started surfacing, the Ninja were tasked with going to Jamanaki village to find the source of the problem. They found out it was Lloyd who caused the trouble and tied him to the top of a sign, embarrasing him. When they went back to the Dojo to train Sensei Wu told them to return to Jamanakai village because the Hypnobrai had been released. Kai and Cole let Nya fight with them as an "Honorary Ninja." Nya got the Hypnobrai staff to the fountain and healed the bewildered and hypnotized villagers, before the ninjas drove the snakes into retreat.

Home
The Ninjas were training when they pointed out to Sensei Wu how Zane seemed strange. When the Mailman arrived Kai and the others discovered Zane was orphaned. The next day Kai and the others went to Lloyd's tree-house which acted as a Hypnobrai base. They started destroying it, but a hypnotized Cole turned on them. Before long Sensei came riding in on Flame playing an ancient flute, which cancelled the Serpentine's powers. The group returned to the monastary on Flame right as the Serpentine set it on fire. Zane and Shard put the fire out but, the monastary was beyond repair. Kai and the others verbally attacked Zane but Sensei Wu caught them reminding them that Zane was they're team mate and had them apologize. But before they could Zane flew off on Shard to follow the Falcon. Kai and the others ate around a fire until Nya noticed Zane entering the camp, at which point he led them to there new home, Destiny's Bounty.

Snakebit
After arriving on the Destiny's Bounty, Sensei Wu makes the ninja clean the area. They do and put all the trash and junk in bin outside. However, later Jay's parents, Ed and Edna, arrive to see Jay there. Kai and the other ninjas tease Jay for his parents eccentric behaviors. After some time however, Ed and Edna leave Destiny's Bounty and go back to there home, located in a Junk Yard. However, the Serpentine are there and attack Ed and Edna. When the Ninja's arrive, they find that they are to late a the Fangpyre have bitten Jay's parents and infected them with venom, transforming them into snake-people. Kai and the other ninja however, are ambushed by the Fangpyre, who have turned the whole junk yard into a snake infected area. Kai and the others defeat the snakes and leave with Jay's parents. After getting Fangtoms staff, Nya uses it to cure Ed and Edna's venom.

Never Trust a Snake
After arguing about who is the green ninja, Kai and the other ninja are forced to train by Sensei Wu as punishment for arguing and not doing there work Kai, along with the other ninja, is confused by Wu's riddle, "What is the best way to defeat an enemy?". Kai fails the riddle along with the other ninjas and assume combat is what Wu was talking about. After training and trying to solve the riddle, it is revealed that a boarding school has been attacked by Lloyd and an unknown Serpentine member revealed to be Pythor. The Destiny bounty takes them their where they drop through the roof of the bulding. Kai and the others chase the panicking Lloyd through the building until they reach the top of the building. As Lloyd and Pythor reach the roof, Kai and the ninja's apprehend Lloyd but Pythor escapes after stealing Lloyd's map. Sensei Wu however influences Lloyd to be good while reading a morale to him.

Can of Worms
Kai discovers that Lloyd has deleted all of his high scores on his video game console. However, Lloyd had done this to the other ninjas as well. Sensei Wu reveals that he put Lloyd up to that to yeach the ninja "the destructive power of rumors". After this turn of events, Nya reveals that she has located the Constricai and Venomari tombs. Kai and Jay take the Venomari tomb while Zane and Cole take the Constrictai tomb. As they arrive, Kai looks around but is intoxicated with Venomari venom and begins to see elves and gingerbread men attacking him. Jay attempts to protect him while Kai is trembling from the visions. Cole and Zane arrive but are followed by Pythor and the Constrictai. As the two tribes surround them, the ninja believe they will not survive the next attack. Kai, hallucinates that a rope is in front of him while he is attacked. Suddenly, Samurai X arrives in a robotic mech and scares away the Serpentine. However, the samurai knocks them unconscious while the Destiny Bounty saves them from the Toxic Bogs. Kai's hallucinations then begin to fade.

The Snake King
Kai offered the ninjas a bet whoever finds the identity of the Samurai X, they are the best and the Green Ninja. His attempt to capture the Samurai fails when he finds her in the Forest of Tranquility and he tries to attack her but the samurai quickly captures him in net. Later when it's his turn to look after Lloyd he drops him off at an arcade hoping to find the Samurai. After Lloyd has been captured by the snakes, Kai, Cole, Zane, and Jay go looking for him at the Lost City of Ouroboros. The ninjas get trapped in a cage that Pyhor set up knowing they would come. Pythor puts them up to the challenge of battling Samurai X. The ninjas are no match for the Samurai so they do the Tornado of Creation and stop the Samurai. Worry the ninjas might win Pythor slides the platform facing a hole. When the ninjas and the Samurai are about to fall the Samurai reveals she hasn't really been fighting with them and she will get them out of there, making her suit fly away with the ninjas clinging to it. When the suit crashes into the desert, Kai gets thrown farther away from the suit and Cole, Jay, and Zane. Seeing the Samurai also crash near him he goes to investigate. He sees the Samurai take off her head gear and recognizes it is Nya and promises to keep the secret.

Tick Tock
After a bet about who can stay underwater the longest, Kai and the others go to ask Wu if they have finally captured their true potential, but find Sensei Wu to be disturbed by something. Kai is corrected, that they have reached full physical potential, but not there true potential. The ninja soon learn of how Lord Garmodon came to be and why it is important to defeat him. Sensei Wu departs while Kai and the others put posters up for Lloyd, who had been captured by the Serpentine. Once the four notice the falcon, they begin to follow it through Ninjago, hoping it will lead them to a Fangblade. After chasing it for miles, the ninja begin to collapse to the ground in exhaustion, Kai finally succumbs to this and allows Zane to follow the Falcon into a snowy woodland. Kai and the others eventually pick themselves up and find Zane to be horrified by something he's uncovered, learning that Zane is an android. Kai and the others still accept him and don't seem bothered by the revelation. After leaving the area, creatures referred to as Treehorns attack the ninja and Kai is defeated by one of the creatures. The queen emerges but is swiftly frozen by Zane, who gains his true potential. The four of them leave the area and return to the Destiny Bounty to discover Wu has not returned from his errands.

Once Bitten, Twice Shy
While watching Nya explain the venom process of a Fangpyre, Jay tries to impress her with men's cologne but finds out that Kai and the others pranked him by giving Jay perfume, which Nya is allergic to. The ninja find that a Fangblade is at an amusement park and prepare to go there to acquire it. Jay attempts to go on a date with Nya at the park but Kai warns him not to, telling him "to get his priorities straight.". The ninja discover a ride that has Serpentine activity near it. The ninja discover the Serpentine excavating the Fangblade and Kai declares a fight. Kai gains the upper hand in the fight along with the others but a mistake on Zane's part causes them to get frozen from one of his attacks. Kai and the others escape their confinement and Jay is revealed to have gained his true potential while Nya is discovered by all the other ninja's to be Samurai X. Kai brags that he is the first to have found this out but the other ninja ignore his arrogance.

The Royal Blacksmiths
The ninja, upset at losing the Fangblade, brainstorm for where the next Fangblade would be. Cole brings up that he knew about a bladed cup that seemed to be a Fangblade that his father once won at a talent show. The ninja go to Cole's Father and disguise themselves as dancers as to not cause suspicion around Cole's dad. They discover the Blade Cup is located at another talent show and enter it.However, the Serpentine have also discovered the Fangblades location and disguise themselves as people in the audience, judges, and performers. When Kai and the others are ready to perform on stage, they began using various dance moves while the Serpentine attack them on the stage. Kai defends himself from them while Cole defeats the others using a new move. The ninja win the talent show and Cole's father discovers that they have no choice but to steal the blade cup because of the real type of object it is. Pythor attacks and nearly kills Cole's father but Cole protects him and gains his true potential while the Serpentine manage to steal the Fangblade.

The Green Ninja
Sensei Wu returns and surprises them by bringing Lord Garmadon, who has now grown multiple arms. Kai attacks Garmadon but Sensei Wu reveals that he is helping them search for Lloyd and scolds Kai for attacking Garmadon. Kai gets more skeptical about Lord Garmadon and at one point overhears a conversation about the Green Ninja between Nya and Sensei Wu. Kai searches for the Golden Weapons and discovers Garmadon is holding them. Thinking he is stealing them, Kai battles Garmadon and "wins". Sensei Wu however reveals he told Garmadon to do that. Kai is dissatisfied to learn that Garmadon allowed himself to be defeated. Kai becomes more and more convinced he is the Green Ninja and believes that only will he gain his true potential when he defeats Lord Garmadon. After discovering the Fangblade is located at the Fire Temple, the ninja go there to get it and rescue Lloyd from the Serpentine. Garmadon fights his way to Lloyd and rescues him but Pythor still has the Fangblade. In a desperate move, Kai impales the Fangblade to the cave wall with his sword, enraging Pythor. In retaliation, the Constrictai cause the lava to rise in the temple. Lloyd falls onto a rock but the Fangblade begins to fall into the lava. Kai chooses to save Lloyd while the Fangblade falls into the pit below them. Kai gains his true potential and realizes that he wasn't meant to become the Green Ninja but save him to gain his true potential. Lloyd is then revealed as the Green Ninja, destined to defeat Lord Garmadon.

Appearance
Kai wears a red ninja outfit, and has brown, spiky hair. He usually has a very determined look on his face. His Minifigure also has some scars on its face.

Personality
Kai is very tempestuous, and often leaps into things before he thinks. He would leap into a lake before checking to see if there's fire in it. At the beginning when he first starting training, he was less interested in teamwork and patience, because of his insistance on finding his sister, but eventually learned to get along with the other ninjas. He is a kind person who cares greatly for his friends and is very protective of his sister Nya. Other characters have noted he has an inflated ego. Although he may be an "act first-ask questions later" type, he'll come through in a pinch. And in the Finale, it seems he has matured greatly and encourages the team to keep fighting.thumb|300px|right

Weapons
Kai currently uses the Sword of Fire, but once wielded a normal katana. In his spinner sets, Kai would also use a double bladed dagger, a flail, a Double scythe, a spear, and a Golden katana.

Trivia

 * Sensei Wu found Kai last.
 * In the TV show (both seasons), Kai is missing his scar on his right eye.
 * Kai thought that he was the Green Ninja (Lloyd).
 * Kai was the last ninja to unlock his true potential.
 * His name Kai means in Hawaiian "Water", as opposed to his element: Fire.
 * Kai's hairstyle is currently the only hairpiece which isn't available as an actual LEGO piece, however the Sleepyhead from the Minifigures theme has a relatively coincidental hairpiece as Kai.
 * His dragon's name is Flame or the Fire Dragon.
 * He is voiced by Vincent Tong.