From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
North Kaio (北 の 界王, Kita no Kaiō; FUNimation "King Kai", Viz "North Kaiō"; Literally meaning "Northern World King") is the overseer of the Northern Galaxy.
North Kaio was Son Goku's final martial arts teacher (although he later taught Yamucha, Tenshinhan, Piccolo, and Chaozu as well) and later mentor. His planet was located above the end of a long winding road known as the Serpentine Road. It was here that he taught powerful, new techniques such as the Genki Dama and Kaio-ken. Despite the fact that his planet was around 100 feet in diameter, the gravity was ten times greater than that of Planet Earth. He had a pet Monkey named Bubbles, a motor-mouth attendant Grasshopper named Gregory, and owned a 1950s-style red Chevrolet Sedan (a nod to the fact that Akira was born in the 1950s). He had a "strong sense of humor", but told very bad jokes, although he possessed great wisdom and knowledge about the universe.
Dragon Ball Z
Main article: Saiyan Saga
Goku arrived on North Kaio's World after months of running along the Serpentine Road in order to train with North Kaio for the coming battle against the Saiyans. North Kaio required that Goku prove himself by telling a joke. He then learned that Goku was not here to train in comedy. Before the training began, North Kaio warned Goku that the Saiyans who were approaching Earth were stronger then North Kaio was, so Goku would need to surpass him if he wanted to stop them.
As part of Goku's training, he told him to chase his pet monkey, Bubbles, who happened to be very fast and had adjusted to the planet's gravity which was simular to the gravity on Planet Vegeta, about 10 times the gravity of Earth. After three weeks, Goku finally was able to catch Bubbles. He then instructed Goku to hit a cricket, Gregory, on the head with a heavy mallet. In time, Goku accomplished this as well. Goku soon found that chasing Bubbles had increased his speed greatly, and attempting to hit Gregory had increased his strength massively, though it should be noted that the second task of hitting Gregory did not appear in the original manga (Gregory did not even exist in the original manga, with North Kaio immediately training Goku directly after catching Bubbles.), and was only in the anime. Right before the Saiyans' arrival on Earth, Goku left for Earth after being revived, with North Kai witnessing the battle. Although Goku completed his physical training, North Kaio sensed he still needed to work on his humor.
Main article: Frieza Saga
Soon after Vegeta retreated, Yamucha, Tien, Piccolo, and Chiaotzu took the journey on the Serpentine Road and arrived on North Kaio's planet, faster than Goku had, for their own special training. North Kaio warned Goku never to encounter Freeza, an intergalactic tyrant and (at the time) the most powerful being in the universe. Yamucha, Tien, and Chiaotzu received training from North Kaio, with Piccolo opting out so that he could do most of the training by himself (believing it to be silly and pointless catching Bubbles in mere seconds, compared to Goku's forty days, since the greater gravity was similar to his techinque of wearing weighted clothing – which he frequently did in his training). He was surprised to see improvements in the other three's skills during a sparring match, however, though this took place only in the anime. As North Kaio witnessed the battle against Frieza, the recently-deceased Ginyu Force, excluding Ginyu, fought against the Z Warriors in training (without Piccolo, who had been revived and sent to Planet Namek) and were defeated by the Z Warriors and sent to Hell, which was rather impressive considering North Kaio considered them to be the most fearsome group in the universe and at least five times stronger than Goku prior to training. This, however, happened in the anime only, and when considering that it took Goku over 150 days to improve to a point where he could defeat Nappa, the weaker of the two Saiyans who were considered to be nothing in comparison to even one member of the Ginyu Force, it seems unlikely that they could have achieved such a dramatic increase in power in such a short time. It may be worth noting, however, that they were able to spar with each other in addition to North Kaio's training whereas Goku was trained alone.
He soon noticed that Frieza was not defeated as originally thought, and Frieza injured Piccolo by piercing his chest and killed Krillin. This heinous action caused Goku to transform into a Super Saiyan. Eventually Goku, in his new form, overwhelmed Frieza, leaving him to attempt to destroy Planet Namek. Although not instantly destroyed (due to Frieza's fear of being caught in its explosion), Frieza estimated that the planet would survive only five minutes longer. With Kami now revived, and the Dragon Balls collected, North Kaio devised a plan to revive all those who had perished at the hands of Frieza and his minions throughout the past year. This would in turn revive Guru, who died because of the pain of seeing his children die by Frieza's great cruelty. Frieza powered up to full power (half of which he was using prior to Goku's transformation) and began to fight Goku. As Shenron resurrected all those who were killed by Frieza, Guru was brought back and Porunga returned in front of the newly revived Dende. North Kaio made telepathic contact with Guru to have Dende ask Porunga to teleport everyone off Namek to Earth, except Frieza. Goku interrupted, and requested that he, too, be left behind in order to ensure Frieza's defeat. North Kaio objected, insisting that Goku's transformation had clouded his judgment, but Goku's determination eventually prevailed. With their plan revised, Guru sent Dende to make the final wish to Porunga to transport everyone off Namek to Earth, except Goku and Frieza. After defeating Frieza, Goku flew to Frieza's ship but found it was too heavily damaged, and seemingly died with the planet. Yamcha informed Bulma through North Kaio of Goku's death. However, Bulma pointed out that with the Namekian Dragon Balls, Goku could be revived, along with Krillin and Chiaotzu, who were both killed twice. North Kaio then said that though Chiaotzu could be revived, Goku and Krillin had died on Namek, and as Porunga resurrects people to the location at which they died, they would die again in the vacuum of space if they were wished back. However, Vegeta suggested voting Krillin and Goku to the Earth's Check-In Station to the spirit world, then wish them back.
Main article: Trunks Saga
North Kaio (as well as everyone else aware of the events transpiring) was shocked when a boy from the future (Future Trunks) arrived and effortlessly defeated Frieza and his father, King Cold, who had traveled to Earth to exact revenge for Frieza's defeat.
Cell Games Saga
Main article: Cell Games Saga
Kami's Fusion with Piccolo had left Earth without a Kami and the Dragon Balls had become inert, so when Goku planned to travel to New Planet Namek to enlist a new Kami, he asked for North Kaio's help in locating the planet.
Later, when Cell had been bested by Gohan in battle, he initiated his self destruction. Having only seconds to react, Goku used Instant Transmission to transport himself and the Artificial Human to North Kaio's World. Cell's subsequent self-destruction killed Goku and North Kaio (as well as North Kaio's pets), who soon realized that Cell must have survived the explosion. With the help of North Kaio's telepathy, Goku provided spiritual support for Gohan, who had been forced to engage Cell once again. Afterwards, Goku tells everyone after declining revival that North Kaio had also declined to be revived so he could guide Goku around the Next World.
Great Saiyaman Saga
Main article: Great Saiyaman Saga
Being dead doesn't seem to hamper North Kaio's affairs, except that it is the source of great embarrassment for him to his fellow Kai's (although he was extremely perturbed at Goku for sacrificing someone as holy as he was for a measly insignificant planet like Earth). On Grand Kaio's World, a tournament is set up in commemoration of North Kaoi's death. Gokū and Pikkon, the student of North Kaio's rival, West Kaio, make it to the finals and Gokū seemingly emerges victorious, until Grand Kaio disqualifies them both for touching the ceiling. It is also important to note, that this entire saga was anime only, and not present in the original manga.
Majin Buu Saga
Main article: Majin Buu Saga
An ancient demon, Majin Boo, is revived thanks to the evil wizard Babidi, the son of the monster's creator, Bibidi. North Kaio witnessed the entire situation. Majin Buu eventually splits into a good and evil personality, with the evil personality winning and absorbing the good one, transforming him into Super Buu. Super Buu exterminates the human race, and several attempts from the Z Fighters to stop him were in vain, absorbing some of the warriors and becoming more powerful. Goku is revived, and merges with Vegeta, who lost his life in an earlier battle with the monster to become the most powerful fighter in the Dragon Ball Z series, Vegito. Super Buu absorbs the fused warrior, separating them in the inside but not fully integrating them. They from the inside, remove the captives within Buu decreasing his power, and the good Majin Buu inside, and escape while Super Buu is changing. Super Buu, however transforms into Kid Buu and destroys the Earth. Goku and Vegeta escape and battle Kid Buu on the Kai Planet. They are quickly losing energy, and even when Majin Buu emerges from Kid Buu, the situation still looks bad. Vegeta comes up with an idea to create the Spirit Bomb, from the Earthlings to destroy Kid Buu. Dende and Kibito Kai travel to New Namek to summon Porunga and wish for Earth's restoration and the revival of the innocents killed since Babidi's arrival on Earth. North Kaio uses his telepathy for Vegeta, Gokū and Hercule, to talk to the people of Earth and persuade them to give their energy to form the Spirit Bomb. Goku fires the Spirit Bomb, but Kid Buu is still showing resistance so the last wish is to restore Goku's strength. Goku transforms into a Super Saiyan and pushes the Spirit Bomb, destroying Kid Buu forever.
Dragon Ball GT
Main article: Dragon Ball GT
North Kaio seems to have got his special planet back after winning the challenge he had made with the West Kaio (when they both put their planets in bet in which if Goku wins, North Kaio gets the West Kaio's World), and warns Goku in the Super 17 Saga, that the dead are escaping Hell. He then assists Goku in forming the Spirit Bomb to defeat Omega Shenron, by forming a universal telepathic link for Goku to ask the beings of the universe to give their energy.
North Kaio appeared in Dragon Ball Z: Battle of Gods.
The attacks he teaches to his students:
- Genki Dama – This attack is arguably the most powerful in the series, depending on who is contributing the energy to it. The user puts their hands above their head and draws energy from all living things into one colossal sphere of energy. North Kaio himself couldn't fully master this, and is astonished when Goku manages to destroy a speeding giant brick with one formed from his little planet.
- Instant Transmission – North Kaio knows this technique and claims he could have taught it to Goku the whole time.
- Kaio-ken – This technique is legendary, as the user is able to unlock the ultimate potential of themselves for a heartbeat, going past what their body should be able to handle normally, to the highest point seen in the series of 20 times the user's base power level. When using this technique, the user's body gets a reddish tinge and they get a strong red aura around themselves. Goku is the only person known to master this technique, as North Kaio himself could not. He also uses it in combination with his Super Saiyan transformation, that Goku called Super Kaio-ken (though this was only seen in the Grand Kai tournament, which was filler. This may or may not be canon)
- Great King Yama
- Kuririn (After being killed by Super Boo, he trains along with Yamucha under North Kaio, however, this is only in the anime.)
- Piccolo Junior
- Son Goku
- Unnamed Kanassan
- Japanese dub: Jōji Yanami
- Ocean Group dub: Don Brown
- FUNimation dub: Sean Schemmel
- Latin American dub: Ricardo Hill
- Portuguese dub: António Semedo
- Gregory says that North Kaio knows everything. This is likely an overstatement by Gregory, who deeply respects North Kaio's abilities. He did not seem to know that Namekians only drink water, telling Piccolo "You're gonna need more than just water." He also was unaware of Cell until Goku mentioned him, and he thought Freeza was dead after his supposed death by Goku (both times). He also thought Goku was dead when Planet Namek blew up. Goku even noted this inconsistency in Dragon Ball Z: Broly: The Legendary Super Saiyan. In the FUNimation dub, after Goku asked about this inconsistency, North Kaio responds that it depends on his mood.
- North Kaio tells Goku to avoid Freeza at all costs as his battle power is nowhere near his. He wants Krillin (who is already dead and could have been erased from existence) to go to Earth and fight Majin Boo (when it seems that Vegetto is dead) when their power difference is greater than that of Goku and Freeza at the moment. This could be due to the fact that Freeza's intent is to rule the universe as opposed to Boo, who would have destroyed not only the physical universe, but the Next World as well and end all of existence due to his insanity.
- North Kaio is the only one of the four Kaios to die.
- North Kaio wasn't revived with the rest of Cell's victims, presumably because Shen Long was instructed to "...revive all those on Earth killed by Cell. Since North Kaio lived and died in the Next World, he would be exempt from the wish. In the manga, it is stated that North Kaio refuses to be revived just for Goku's sake so he could escort him in the Next World.
- It is revealed in the Cell Games Saga that North Kaio has the ability to use Instant Transmission, but earlier in the Saiyan Saga after Goku had finished his training under North Kaio he told Goku he would have to travel back along Snake Way in order to get back to Earth to help defeat the Saiyans in the time instead of simply taking him there himself or at least to the Check In Station like Goku had assumed. It is possible that North Kaio learned the Instant Transmission after this in order to avoid such a situation in the future though he mentioned he could have taught Goku it himself when he went there, learning the location of the Nameks.
- In Weekly Shōnen Jump, it is stated that North Kaio has a battle power of 3,500 – the same as Piccolo in his battle against Nappa.