When the Oni finally invade, the ninja team up with Lord Garmadon, and Kai and the rest of the ninja fight to defend their home. Afterward, he along with the other ninja attend the celebration and Kai and Skylor share a moment.
![enter the ninja musikvideo enter the ninja musikvideo](https://thedrunkenodyssey.files.wordpress.com/2015/07/eninja4.jpg)
Upon returning, along with his fellow ninja, he takes down Garmadon's Colossus while Lloyd defeats his father, restoring peace to Ninjago once again. After Iron Baron is defeated by Firstbourne, Wu reclaims the Dragon Armor, in turn allowing them to return to Ninjago. Kai and the ninja help save the various dragons from the Dragon Hunters and help the now-teenage Wu regain his confidence and memories. Despite the ninja's efforts, Harumi successfully resurrects Garmadon, and shortly after, Kai ends up marooned in the Realm of Oni and Dragons, which is also known as the First Realm, with Cole, Jay, Zane, and the de-aged Wu. They later discover that she secretly is the leader of the Sons of Garmadon and wants to resurrect Lord Garmadon. Kai and the ninja later watch over Princess Harumi after she lost her adopted parents. They managed to track them through time and stopped them before Wu sent Kai and Nya back to the present, while Wu ended up lost in the time. Kai and Nya reunited with their parents and stopped Krux and Acronix from changing the future. When the Time Twins returned to Ninjago, Krux tried to convince Kai that Kai's parents were traitors.
![enter the ninja musikvideo enter the ninja musikvideo](https://images-na.ssl-images-amazon.com/images/I/71-Fd3-WpRL._RI_.jpg)
The siblings defeated Chen before going to Yang's Temple, where they witnessed Cole become a human. On the Day of the Departed, Cole accidentally revived the Ninjas' old enemies, including Chen, who attacked Kai and Nya. Kai witnessed Nya die after being struck by Tiger Widow venom, though Jay's final wish reversed recent events, saving her. During their first encounter, Nadakhan trapped Kai in the Sword of Souls, though he was later freed by Jay. Yet they found themselves facing a new problem when Nadakhan returned with the Sky Pirates. The Ninja found fame after saving Stiix, with Kai becoming obsessed with his popularity. The Ninja battled Morro and his forces at Stiix before the Cursed Realm was destroyed. Soon after the war's end, Lloyd was possessed by Morro, who escaped the Cursed Realm and released a legion of ghosts. There, they competed in the Tournament of Elements before allying with the other Elemental Masters to defeat Chen's army.
![enter the ninja musikvideo enter the ninja musikvideo](https://static.metacritic.com/images/products/movies/7/d126029fbbc130d24869349956f8644b-250h.jpg)
The Ninja team separated until Lloyd reunited them to rescue Zane on Chen's Island. The Ninja fought the Overlord and his Nindroids until Zane sacrificed himself, vanquishing the Overlord but seemingly dying in the process. After Lloyd defeated the Overlord and his father was purified of evil, peace resumed in Ninjago until Pythor returned, aiding The Overlord in becoming the Golden Master and commanding the Nindroid army. Kai and the Ninja soon fought the Stone Army in a desperate effort to prevent the final battle, which was soon made all but certain.
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With the help of a wise master, Wu, Kai learnt Spinjitzu and discovered his three other teammates, with whom he embarked on many adventures with as they battle the Serpentine and eventually The Great Devourer. Kai and Nya continued to work as blacksmiths in their missing father's shop. He is the Elemental Master and Ninja of Fire, and Nya's older brother. Kai is the main protagonist-turned-overall deuteragonist of LEGO Ninjago: Masters of Spinjitzu. I'll lead them and I'll shut you down if it's the last thing I do.