Kai Kai is the red ninja of fire minifigure released in 2011 as part of the Ninjago theme . Sensei Wu entrusted the map to the golden weapons to Kai ' s father . Kai is the Ninja of Fire and the strongest of the four and is also the brother of Nya . He was a ' blacksmith ' before apprenticing himself to Sensei Wu to save his sister Nya . Kai is fiery in both fighting style and temper , and a very independent character . However , he eventually gained control over his impulsive tendencies . Description . Variants . Kai , like the other ninja , has many different variations . Regular 2011 Variant . Kai ' s original suit , which appeared in several sets in 2011 , is almost entirely red . His legs are red , printed with a dark red sash , which is also printed on his hips . His torso is also red , with black hands . It is printed with several dark red sashes , which are connected to a gold badge , that looks rather like a lion . His face is yellow , and shows a determined expression . It has several red scars running across it . He wears a red ninja wrap . DX . Kai ' s DX variant is , fairly similar to his regular version , but with notably different printing . The DX version ' s lower section , like those of the regular one , are printed with a sash on the legs and hip , but , unlike its predecessor , it has a fiery dragon tail printed on it . The torso is pure red , with black hands , and a fiery dragon printed on it in gold . On the back of the torso , is printed Kai ' s name . The face and wrap used on the variation are identical to those used previously . Kendo . This version of Kai , first introduced in 2012 , has Kai ' s basic legs - that is , red , printed with a sash . The torso has black hands , and is covered with kendo armour , but , underneath , is exactly the same as that used by Kai ' s basic variant in 2011 . His head is , again , the same that is used by his basic variant , but , instead of a ninja wrap , he wears a kendo helmet , which bears a distinct resemblance to a grilled hockey mask . ZX . Kai ' s ZX variant has red legs printed with the bottom of a tunic , and a red torso ( with dark red arms and black hands ) , printed with a tunic , dark red armor , and a dark red belt ( with an unidentified silver tool in it ) . He wears around his neck a sheath - like object , which katanas can be stuck into . His face is he same as that used in all his prior variations , but his wrap is notably different , as it has a large gold ornament attached to it ' s front . Another version of the ZX suit is available , that has a large jetpack attached to it ' s back in place of the scabbard . NRG . NRG Kai has red legs , a red torso with a large explosion printed on it , and a red face with a rather demonic expression . His wrap is similar to the one used by his ZX form , but has a thinner ornament that resembles fire . Elemental Robes . Kai wearing his elemental robes appears in Island of Darkness and is exclusive to the set 70500 Kai ' s Fire Mech . Techno Robes . Kai obtains the Techno Robes from Cyrus Borg in order to block the facial recognition system the Overlord has on his robots . Unlike the previous variants , it is only a half - mask and reveals his hair . This variant also does not have shoulder armor . It appears in the sets 70721 Kai Fighter and 70727 X - 1 Ninja Charger . Tournament Robes . Microfigure . As a Microfigure , Kai is exclusive to the set 3856 Ninjago . He is composed of a single red piece , which is moulded with bumps to represent arms and legs , and printed with his red clothes , a gold badge , and a sash , as well as the small portion of his face visible under his wrap . Alarm Clock . As an alarm clock ( the set 9003097 Kai Minifigure Clock ) , Kai is very similar to his basic form from 2011 , but he is considerable larger , made out of a single part ( although his limbs can be moved ) , and has a digital clock - face in his chest . Blacksmith . Kai as a blacksmith only appears in the televised version of Ninjago , Set The Four Weapons Blacksmith Shop from 2011 , and in . He has fairly basic legs , a white torso printed with a heavy - duty apron , his basic face , and in the video game , brown Exo - Force hair . Variation history . Kai ' s original variation was a basic " ninja suit " . It has no special powers , and was given to him by Sensei Wu . His second variation , his DX version , was a special suit , received after he has met his dragon , and found the Sword of Fire . His kendo variation , used after that , was his regular variation , but with extra armour , for use in training . His ZX version arrived mysteriously in the mail , and is an upgraded version of his regular suit . In the episode " The Green Ninja " Kai unlocked his full potential and turned into his NRG variant by saving Lloyd Garmadon in the Fire Temple instead of getting the fangblade . His Elemental Robe was unlocked when the ninja made it to the Temple of Light and Lloyd struck the " instrument of peace " . Background . Before the Ninja . Before Kai became apprenticed to Sensei Wu as a ninja , he and his sister Nya worked in their family blacksmith shop , " Four Weapons " , which had previously been owned by their ( now deceased ) father . Introduction to Spinjitzu . Once , when Kai and his sister , Nya were working the " Four Weapons " blacksmith shop , they were approached by Sensei Wu , who showed disdain for the weapons they made , claiming that they would be useless in the art of stealth . He also said that they were fit weapons for a samurai , but useless for a ninja . Kai drove him off , but he then disappeared when Kai turned his back . Moments later , a dark cloud appeared over the village , which local farmers were the first to notice . On the edge of a hill , a large vehicle ( the Skull Truck ) appeared along with many motorcycles , all with skullkin aboard them , notably General Nuckal , Kruncha , and Samukai . The farmers attempted to attack the skullkins , only to run away at the last second . Then , Kai , wearing hand - crafted samurai armour , helmet , and sword , engaged the skullkin in battle , with Nya joining in . Kai was nearly killed by Samukai , only to be saved by Sensei Wu , who reappeared just in time . He was not able to save Nya , who was kidnapped under the orders of Lord Garmadon . Sensei then told Kai the history of Ninjago . After telling Kai the story , Sensei told Kai that his father had a map made by Wu , showing the locations of the hidden Golden Weapons , and also that Garmadon had struck a deal with Samukai , and that Wu was Garmadon ' s younger brother . Kai at first refused to get involved , until realizing he wouldn ' t stand a chance against the skullkin on his own . He then trained in Wu ' s monastery , and , after completing his training , awaited a final test , but is told he had already learned spinjitzu . Later that night , Kai was ambushed by three ninjas , and the ensuing battle causes him to be thrown out onto the training grounds . Kai activated the training course and the obstacles disarmed his attackers . Moments later , Sensei Wu stops the fight , revealing that the three are his other students . Sensei then uses spinjitzu to transform their black suits into outfits corresponding with their element . The four are introduced to each other : Cole , the black ninja of earth ; Jay , the blue ninja of lightning ; Zane , the white ninja of ice and a seer with sixth sense ; and Kai , the red ninja of fire . Introductions were cut short as Wu announced the search for the golden weapons had now begun . The Search for The Golden Weapons . Their first destination of the ninja was the Caves of Despair , where the Scythe of Quakes was hidden . Here , Kai raced off in hopes of finding his sister . Instead , he nearly was caught by the skullkin Krazi , who would have raised the alarm , but the other ninja got there in time , and shoved his Bone weapon into his mouth . As the four captured the Scythe , they were attacked by Samukai and a whole legion of skullkin . Jay noticed that the enemies were just like the training course , and after going through the motions Wu taught him , he summoned a tornado of energy corresponding with his element , lightning . In so doing , he performed spinjitzu , and was quickly copied by the others . Samukai and his legion retreated , as they saw the Earth Dragon , guardian of the Scythe appear behind the ninja . In desperation , Kai used the scythe , despite Wu ' s instruction not to use the weapon ' s power , as no mortal could handle it . A rift appeared in the cave ceiling , and the ninja managed to escape . Wu became quite angry at Kai for using the weapon ' s power . As the ninja were aboard a boat , sailing to reach the desolate frozen planes in which the Shurikens of Ice were to be found , Wu taught them the most powerful move in spinjitzu : the Tornado of Creation . The boat arrived at it ' s destination , crashing into the island , and the ninjas entered the frozen plains . The group yet again escape a dragon guarding the weapons , and , as Zane was frozen upon contact with the shurikens , the others used him as a snowboard . With the shurikens being in their possession , they continued on . At the Floating Ruins , they climbed a giant chain to the Nunchucks of lightning , retrieving them , but being forced to jump off of it to escape the lightning dragon . The four survive this experience because of special inventions made by Jay , backpacks that spawn wings . The ninja were at such a high altitude when they jumped , that they were able to fly to all the way to the Forest of Tranquility , the location of the Sword of Fire . After a long day ' s work , everyone fell asleep . Kai was then awoken by none other than Nya . She ran away , and Kai chased her through the forest , eventually entering the Fire Temple . Battle with Lord Garmadon . The other ninjas then traveled to the Fire temple , where Zane sensed the Sword of Fire was . Kai and Nya then appeared with the Fire Dragon . After the others got the dragons of their respective elements to assist them , they go to the underworld , where they then battle an army of skullkin and giant spiders , using the Tornado of Creation . Kai and the other ninjas then entered Garmadon ' s throne room where they witnessed Samukai defeat Wu . Samukai then grabbed the Sword of Fire . He planned to destroy Garmadon with the weapons , but soon disintegrates from all of the power streaming into him from all the Golden Weapons , and in his place is created a portal which Garmadon goes through , and escapes the underworld . When he is gone , Sensei Wu informed the ninja that he will return one day . The four ninja then return to Kai and Nya ' s village , where they are welcomed by Nya and the villagers as heroes . Awakening of the Serpentine . After a long period in inactivity following Garmadon ' s escape , Kai and the other ninja went to investigate a report of his return . They went to Jamonicia village and see Lloyd Garmadon , his son , terrorizing the villagers . After the ninja defeated him and left him to the villagers , Kai found a scroll telling of the coming of the mysterious Green Ninja , the most powerful ninja of all . He asks himself if it is possible that he will become him . To determine , he challenges the other ninja to a fight . After beating Jay , he faced off against Cole , during which his sword nearly burned down the entire monastery . Afterwords , Sensei Wu announced that the the Serpentine , an ancient and dangerous race of snake people are back , and are terrorizing Jamonicia village . The ninja return there , and encounter the Hypnobrai tribe of Serpentine , who have been awakened by Lloyd . Kai ' s appearance in this battle is limited , and shows that his Spinjitzu is too unstable to control . After the battle , he asks Sensei Wu to teach all of them the secrets of the golden weapons . Afterwards , he and the other ninjas made fun of Zane for his odd behavior . Zane then discovered Lloyd Garmadon ' s tree - house , and lead the other ninja their . After Cole , who was hypnotized by Skales of the Hypnobrai , is pitched against the others , Kai refuses to use his sword in fear of destroying the entire place . After Sensei Wu un - entrances him , they return to see the monastery in flames . Kai is the first to turn on Zane . After Zane flies off , Kai and the other ninja take shelter , and then see Zane approaching them . After he explains that he flew off to see his falcon , he leads them to their new home , the ship Destiny ' s Bounty . Later , on the ship , Jay ' s parents , Ed and Edna Walker , come to visit . Jay manages to get them to leave , but promises to visit them at their junkyard the next day . He and the other ninja then go there , only to find the place overrun with members of the Fangpyre tribe , another breed of Serpentine , once again awoken by Lloyd . Kai and the other ninja defeat the Fangpyre , and Nya creates an anti - venom to their poison . During training a day or so later , Sensei Wu asks the ninja a riddle : " What is the best way to defeat an enemy ? " Kai answers " to train " , but is incorrect . Later , the ninja discover that Lloyd , with the aid of the Serpentine Pythor P . Chumsworth , have taken over the Boarding School for Bad Boys , from which Lloyd was expelled . The ninja arrive at the school , and rescue the captured students . The ninja corner Pythor and Lloyd on the roof , and Pythor steals Lloyd ' s map ( which shows the locations of the other tribe ' s tombs ) , and escapes , leaving Lloyd to the ninja . Later that night , after Lloyd has fallen asleep , Sensei revealed that the answer to his riddle was " To make them your friend " . Samurai X . At Sensei Wu ' s orders , Lloyd played various tricks on the ninja , one of which mixed up Kai and Zane ' s uniforms in the laundry , turning Zane ' s pink . Shortly after this , Nya discovered and revealed the location of the tombs of the Constrictai and Venomari . The ninja split into two teams , Kai and Jay teamed up to find the Venomari Tomb , and Zane teamed up with Cole to find that of the Constrictai . On their mission , Kai and Jay were attacked by Pythor and the Venomari ( The Venomari spit venom into his eyes not only making him a bit Waco . , but also makes him see what he fears : elves , and gingerbread people ) , but were saved by Samurai X , who then drugged them with knock - out gas . To stop the Serpentine tribes uniting , the ninja traveled to Ninjago city , where the Serpentine had gone . However , they were all captured except Zane , who later freed them , and used the Shurikens of Ice to help them escape . One day , a package arrived for the ninja , containing new ZX suits , which the ninja put on . Nya then told the ninja that the Serpentine had invaded the Mega Monster amusement park . However , by the time they got there , they find the serpentine tied up and helpless . It was then revealed by several onlookers that a samurai captured the snakes . The ninja then decide that whoever finds out the identity of Samurai X first should become the green ninja . Later , Kai is forced to baby - sit Lloyd . Determined to find out the identity of the samurai , he leaves him at an arcade . Later , back at Destiny ' s Bounty , Sensei Wu asks where Lloyd is , and Kai realises that he is missing . He and the other ninja are then sent to find him . They discover his tracks sometime later , and , by following them , find the city of Ouroborous , where Pythor has just taken over the tribes of Serpentine . Naturally , the ninja try to rescue Lloyd , but are captured , and forced to fight Samurai X . After a long fight , the ninja and the samurai agree to work together to escape . The samurai uses the rockets in her mech - suit to escape , and the ninja grab on , and are flown to safety . However , after they have been dropped off , the mech - suit malfunctions , and falls to the ground . Kai , who was separated from the rest of the group , went to investigate , and discovered that the samurai was none other than Nya . However , Nya swears him to secrecy , asking him not to tell anyone the truth about her . The Great Devourer . In the course of a battle against the Treehorn s , Zane discovers that he is a robot , and unlocks his full potential , becoming an NRG ninja . The same day , Sensei Wu tells a story of The Great Devourer , a giant evil snake , and how its venom corrupted Lord Garmadon when he was young . Wu then leaves the ninja to find Garmadon . Later Kai discovered his full potential when he saved Lloyd Garmadon instead of going after the fang blade . Back in Time . Once taking the golden weapons , Lord Garmadon goes to the Golden Peaks , the birthplace of the golden weapons and combines their power creating a Mega Weapon . The Mega Weapon then gave Garmadon the power to grant him any whish but drains his power every time he uses it . In the episode " Wrong Place , Wrong Time " , Lord Garmadon uses the Mega Weapon to go back in time and make it so that Lloyd would never become the green ninja . The ninja later find out about his plan and jump into the portal Garmadon created with his Mega Weapon to stop him . The ninja get back in time and fall through a portal . They find themselves in Ignacia , at the time Wu came to Kai ' s shop and even before Skulkins attacked the land . They catch old Wu and explained him about the situation . This time , skeletons didn ' t kidnap Nya and Kai from the past had no will to become a ninja . Wu then leads him and Nya to the monastery . Ninjas decided to dress like skeletons and kidnap Nya so past Kai can get a reason to become the ninja . They did that , and Garmadon took Nya to the Fire Temple . Present Kai reveals himself to his past self , and they work together to defeat Garmadon . They success by destroying the Mega Weapon and Kai , along with other ninjas comes back safely . The Invitation . After Zane had sacrificed himself to save every one from The Overlord ' s and the Ninjdroid ' s plan , Kai had left the team and has become a masked fighter who competes in an underground Slither Pitt . He competes under the alia the Red Flame . He fought Kruncha in the ring and won . Lloyd showed and try to convince him to return . He later shows up Chen ' s Noodles during Lloyd ' s second attempt at getting the gang back together . While their they to stop a robbery only to find out Zane is alive and is on an island where an elemental tournament is being hosted . When the gang reunite to board the boat he encounters two elemental masters , One who he develops a crush on the girl named Skylor a mysterious elemental user . And develops a rivalry with Karlof The Elemental Master of Metal , who wears large gauntlets .