King Kai's Planet (界王の星 Kaiō no Hoshi, lit. "Boundary King's Planet"), also known as North Kai's Planet (北の界王の星 Kita no Kaiō no Hoshi, lit. "North's Boundary King's Planet"), is a planet located in the Other World. It is home to King Kai, ruler of the North Area, as well as to King Kai's pets: Bubbles and Gregory.
This planet is the home of King Kai. Its most notable feature is that its gravity is roughly ten times the strength of Earth's, making it an ideal training ground. The planet used to be about 100 times that of its current size, although it is unclear if this implies a higher gravity, but given the planet's peculiar "size to gravity" ratio, it likely was the same. The planet contains nothing but a grassy surface, a half dozen or so trees (some of which bear fruit), a road that circumvents the planet, King Kai's house, his car, a well, and some other small building. The God of Destruction Beerus had visited King Kai's planet 327 years prior to the events of the God of Destruction Beerus Saga. During his visit, Beerus and King Kai played a game (either a car racing video game or a "spirited game of hide-and-seek" depending on the version). Upon Beerus' loss, the God of Destruction destroyed the planet, leaving it significantly smaller. In "Showdown on King Kai's World! Goku vs. Beerus the Destroyer!", Beerus destroyed the planet because he didn't like the food.
After Goku sacrifices himself for Piccolo to kill Raditz, he is taken to the Check-In Station by Kami. Kami asks King Yemma to allow Goku to travel down the Snake Way and train with the legendary King Kai, so that he will be prepared to battle the Saiyans when they arrive on Earth in one year. King Yemma accepts and Goku spends many months running on Snake road, heading toward the planet. Upon arrival, Goku's skills are put to the test, he was assigned to catch Bubbles (which proved a daunting task considering the gravity) and to hit Gregory with a hammer (which was fairly hard to hold let alone swing). He passes these tests and is permitted to receive King Kai's training. In the next few months, Goku masters the Kaio-ken technique and the deadly Spirit Bomb, moves that will be essential in his battle against the Saiyans. Afterwards, the fallen Dragon Team: Yamcha, Tien Shinhan, Chiaotzu, and Piccolo are given permission to keep their bodies, and travel down Snake Way to receive training with King Kai while their friends are dealing with Frieza on the planet Namek. Goku later visits the planet during the ten day wait for the Cell Games to ask for directions to New Namek, and was also summoned by King Kai to deal with a Super Saiyan that destroyed the South Area.
The next time the planet is actually visited in the main story is when Goku teleports Cell to it as he is about to self-destruct. This kills King Kai, Bubbles, Gregory, and even Goku. Cell manages to survive, and returns to Earth, only to be finally killed by Gohan. King Kai, his pets, and Goku then all travel to Grand Kai's Planet. Due to Cell's self-destruction (and thus King Kai's death), the space pirate Bojack and his gang of Galaxy Soldiers are unleashed, leading up to the events of Dragon Ball Z: Bojack Unbound. In Dragon Ball Z: Battle of Gods and Dragon Ball GT, King Kai's planet is shown to have been brought back. In Battle of Gods, the God of Destruction Beerus tracks down Goku, the Saiyan who defeated Frieza, and accepts the challenge from Goku to see how strong he is. When he arrives on the planet, the God of Destruction complains that King Kai's planet is so small, but his attendant Whis reminds him that he is the reason it is so small for destroying it when getting mad after losing at hide-and-seek.
In a bonus chapter for Dragon Ball Super's manga, sometime before the series, King Kai asks for Moori's permission to use the Namekian Dragon Balls to revive his planet. King Kai thinks of having a bigger planet with a race track, a beautiful house, and less gravity. Goku shows up and uses the wish to keep it the same as was previously because having ten times gravity is great for training.
- Apple trees
- King Kai's house
- King Kai's 1957 Red Chevrolet Bel Air Hardtop (when he gets bored, King Kai likes to drive around the planet in this car)
- King Yemma – Traveled to receive training.
- Goku – Visited numerous times throughout the series, but mainly to receive training to battle the Saiyans after he sacrificed himself to have Piccolo use the Special Beam Cannon on Raditz. Partially responsible for its destruction during the Cell Games when he transported Semi-Perfect Cell to prevent his self-destruction from destroying the Earth apologizing to King Kai after doing so stating it was the only place he could think to take him where the damage would be minimal. Was responsible for it being restored by Porunga to the way it was before it was destroyed during the Cell Games much to King Kai's annoyance as he wanted a larger planet with less gravity. After it was restored Goku had a habit of visiting the planet to train though this tended to result in it being repeatedly damaged by Goku's intense training as well as during his initial fight with Beerus.
- Raditz – Killed by Piccolo's Special Beam Cannon due to Goku's sacrifice. Was given a special invitation by King Kai so Goku could be assured that his training is helping him (Budokai Tenkaichi 2 only). Was later given a special invitation by King Kai again, alongside Nappa, to assure one of his students that his training was indeed helping him. This time, the student in question was Piccolo (Dragon Ball Z: Super Saiya Densetsu).
- Nappa – Killed by Vegeta's Galaxy Breaker. He and Raditz were given a special invitation by King Kai so Piccolo could be assured that his training is helping him (Dragon Ball Z: Super Saiya Densetsu only).
- Piccolo – Killed by Nappa after protecting Gohan from the Saiyan's Bomber DX. Trained on the planet after making the journey across Snake Way before being revived and summoned to Namek by Porunga at Piccolo's request so he could join the fight against Frieza despite King Kai's opposition to Piccolo and the others confronting Frieza.
- Tien Shinhan – Died after giving off all his energy in an attempt to kill Nappa. Trained on the planet after making the journey across Snake Way before being revived by Porunga and returned to Earth.
- Yamcha – Killed by a Saibaman's Saibaman Bomb. Trained on the planet after making the journey across Snake Way before being revived by Porunga and returned to Earth.
- Chiaotzu – Blew himself up in an attempt to kill Nappa. Trained on the planet after making the journey across Snake Way before being revived by Porunga and returned to Earth.
- The Ginyu Force (barring Captain Ginyu) – Killed on Planet Namek by Vegeta. Were given a special invitation by King Kai so his students (Yamcha, Chiaotzu, and Tien) can be assured that their training is helping them. Later defeated and sent falling straight into Hell.
- Cell – Forced there after Goku used Instant Transmission in order to save the Earth from Cell's self-destruction. Regenerated and regained his Perfect form without 17 or 18 (as 17 had been killed by his self destruction and 18 had been spit out previously) thanks to his Saiyan cells and used Instant Transmission to return to Earth where he was killed by Gohan and sent to Hell by King Yemma.
- Olibu, Sarta, Mijorin, and various other northern galactic heroes – All died under unknown circumstances (however the only one heard of was Olibu).
- Beerus – Came by to visit King Kai, and ended up destroying the original planet. He revisited many years later and fought Goku.
- Whis – Came to the planet with Beerus.
- Android 17 – Forced there after Goku used Instant Transmission in order to save the animals from the leader's self-destruction.
- Galactic Poachers Leader – Forced there after Goku used Instant Transmission in order to save the animals from the leader's self-destruction.
- Future Warrior - Briefly visited the planet to pick up Goku in an altered timeline where he mistakenly assumed the Tournament of Destroyers was on a different date in Dragon Ball Xenoverse 2 after they and their partner Trunks: Xeno had located Goku using the Time Scroll. Event disappeared from history once the timeline was corrected by the 2nd Future Warrior with Goku defeating Hit in the final match if the Tournament as Monaka had been withdrawn by Beerus (history was corrected as Team Universe 7 won regardless and the original timeline was restored by Chronoa putting the scrolls back together following its successful correction).
- Gravity — 10g (10 times the Earth's gravity).
- Diameter — King Kai's car, the 1957 Chevrolet Bel Air, has a length of 196 inches (5 meters). This screenshot shows the Chevrolet covering about 8% of the planet's diameter, meaning the planet has a diameter of about 63 meters.
- Radius — 31.5 meters (half of diameter).
- Volume — Spherical volume of 130,924.303 cubic meters (radius of 31.5 meters cubed and multiplied by 4/3 ).
- Mass — Using the equation, the gravity (98.1 m/s2) multiplied by the radius squared (992.3 m2), divided by the (6.67×10−11), gives the planet's mass as 1.458x1015 kg.
- Density — The planet's Sun's density (1400 kg/m3) and 1.11–111 times the density of a star (10 million to 1 billion kg/m3). (mass per volume) is 1.11 billion kg/m3. King Kai's planet thus has 7,954,432.78571 times the
- Pressure — The amount of pressure required to a cubic meter of the Earth's crust, which mostly consists of silicon, would be about 3000 s per kg/m3 of density. With 1.14 billion kg/m3 of density, the amount of pressure required to break a cubic meter of King Kai's planet would be about 3.42 trillion megapascals.
Video Game Appearances
King Kai's planet is visited in Dragon Ball Z: Kyōshū! Saiyan, Dragon Ball Z: Super Saiya Densetsu, Dragon Ball Z: Goku Hishōden, Dragon Ball Z: The Legacy of Goku, Dragon Ball Z: Harukanaru Densetsu, and Dragon Ball Z: Attack of the Saiyans.
It is seen during King Kai's appearances in Dragon Ball Z: Goku Gekitōden, Dragon Ball Z: Super Gokuden: Kakusei-Hen, Dragon Ball Z: Budokai, Dragon Ball Z: Budokai Tenkaichi 2, and Dragon Ball Z: Infinite World. The planet is seen in the background of the Snake Way stage in Dragon Ball Z: Taiketsu.
In Dragon Ball Xenoverse 2 during the Battle with Universe Six Saga, a history change causes Goku to mistakenly believe the Tournament of Destroyers is on a different date causing him not to be present when Team Universe 7 leave for the Tournament of Destroyers making him a no show along with Majin Buu whom was also absent for unknown reasons. Old Kai and Chronoa task Trunks: Xeno and his legendary partner the Toki Toki City Hero of the Time Patrol to locate Goku and bring him to the Nameless Planet. Trunks: Xeno and his partner manage to locate Goku training for the tournament on King Kai's Planet and the Toki Toki City Hero is sent to inform him the tournament is already underway and escort Goku to the Nameless Planet. Chronoa explains to Beerus where they found Goku and casually refers to it as King Kai's Place. King Kai's Planet isn't actually shown only mentioned in passing by Chronoa.