I was originally thinking of having this be part of the universe section of my “Hitchhikers Guide” thread, but it got to be such a long tangent that I decided to split it off into it’s own thing. There’s always been a lot of confusion over how many galaxies the DB universe consists of, and just how the Kaios and Kaioshins fit into all this. The old DB fansite Planet Namek.com, which was extremely popular and influential back in the day, had an explanation of the whole thing that was extremely wrong, and that’s been muddling the issue ever since. So let’s go through this bit by bit.
The SeriesThe first time galaxies are ever mentioned in the series is when North Kaio talks to the Great Elder during Super Saiyan Goku and Freeza’s battle. Previously, Kaio had always simply been called “Kaio”, and the guide oni who took Goku to the Serpent Road explained that Kaio “stood above all the gods in the universe”. However, Kaio introduces himself to the Great Elder as “the Kaio of the North Galaxy” (北銀河の界王/
kita-ginga no kaiou; in Viz he says “god” instead of “Kaio”). There’s no real plural in Japanese, so “North Galaxy” could also possibly be “North Galaxies”.
It’s not until the Boo arc that Kaio’s line is expanded on. While Goku trains in the afterlife for the 25th Tenkaichi Budoukai, the South Kaio appears to observe his training. Rather than “galaxies”, the South Kaio talks about “Areas” (エリア/
eria). Goku is said to be the first or second strongest warrior from the North Area, and South Kaio mentions his own South Area (in Viz, “Area” isn’t used, and they simply say “the North” and “the South”). It’s not clear how Areas relate to galaxies. Earth is also said to be in the North Area, so Areas aren’t just some division for the afterlife.
Shortly after South Kaio appeared in the manga (chapter 428, July 12th, 1993), all 4 Kaios appeared in the Afterlife Tournament filler arc, which premiered July 18th, 1993. In this arc, it’s explained that there are four Kaios, who rule the North, South, East, and West Galaxies, respectively (but the lack of a plural in Japanese kicks in again here: West Kaio, for instance, could be in charge of either the West Galaxy or West Galaxies). Above them is the Dai-Kaio, their ruler. It seems that Toriyama was fairly involved in this filler arc, since he drew a map of the DB cosmos for the first time so that it could be used for this storyline, and personally did the Dai-Kaio’s character design. In fact, the Dai-Kaio is mentioned in the anime about three months before he is in the manga: it’s not until Shin’s true identity is revealed that Piccolo explains that the Dai-Kaio is the one who stands above the 4 Kaios (chapter 440, October 11th, 1993). So Toriyama was almost certainly involved in coming up with the back-story for the Kaios for those filler episodes.
The GuidebooksSo basically, the series itself establishes the each Kaio rules the galaxy/galaxies of a cardinal direction, and that there are also “Areas” corresponding to the cardinal directions involved somehow. Toriyama’s map of the DB world labels the universe as being divided up along the 4 cardinal directions, but says nothing of galaxies or "Areas". Essentially there are two possibilities: that there are 4 galaxies (NSEW) that are also called “Areas”, or there are 4 Areas (NSEW), that contain many galaxies. The guidebooks all go with the first option (when they don’t just leave the whole thing as vague as the manga, that is): Daizenshuu 7 twice says that there are 4 galaxies. DBZ Son Goku Densetsu and the Super Exciting Guide: Character Volume both say so too. Of these, the only one to even mention "Areas" is Daizenshuu 7. Unfortunately, it isn’t terribly helpful on explaining what if anything is the difference between a Galaxy and an Area: it describes both as ways the gods divide up the universe along the 4 cardinal directions in order to govern it, but says nothing on how the two terms relate to each other. Since it says that galaxies in DB are simply administrative units used by the gods, and therefore have little if anything to do with the real-world astronomical term, perhaps “Area” is the more accurate term that the Kaio use when talking among themselves (like with North and South Kaio), while “galaxy” is a more descriptive term they use when talking to the universe’s inhabitants (like with North Kaio and the Great Elder)?
The KaioshinsWith the Kaioshins, originally there’s just supposed to be one, who Piccolo says stands above even the Dai-Kaio, and serves as a god to the gods. Very shortly thereafter, when explaining about Boo, Kaioshin himself says that there used to be 5 Kaioshins, but all the others besides him were killed by Boo. It’s not until just before the final battle with Boo that Kaioshin expands on this: the 5 Kaioshins were organized just like the Kaios, with 4 Kaioshins for the cardinal directions, ruled by 1 Dai-Kaioshin. Kaioshin himself was the East Kaioshin. The manga doesn’t say just what significance these cardinal directions have, however.
Where do the Kaioshins fit into governing the DB universe? It’s never explained in the series, but since the Kaioshins have exactly the same titles as the Kaios, and Toriyama’s map shows the universe only divided into NSEW with no sub-divisions, the simplest explanation is that they also govern the 4 galaxies/Areas of the universe. If you've got a "Kaio of the North" and a "Kaioshin of the North", unless told otherwise it makes sense to assume that "the North" in each one's title refers to the same territory. The obvious question then is what point do the Kaioshins serve? The manga only gives the vague explanation that they are the gods of the Kaios (which is what the term
Kaioushin itself means), but the daizenshuu and SEG offer a little more to that, saying that while the Kaios only govern the universe, the Kaioshins govern both the universe and afterlife as well. What’s more, Toriyama explained in the SEG that the Kaios and Kaioshins are members of a race called Shinjin (Pit People), who are born from the fruit of the Kaiju Tree (World-Tree). Kaios are chosen from among regular Shinjin, while Kaioshins are chosen only from special Shinjin born from a rare golden Kaiju fruit. So the division between Kaios and Kaioshins is based on this natural division in the Shinjin race.
Planet Namek.comSo I said at the start that Planet Namek.com gave an incorrect explanation of the DB universe and god hierarchy. This spread pretty far around the internet (it’s been reused on
MFG’s Universe Page, for instance). While the series only ever mentions 5 Kaios and 5 Kaioshins (counting the Dai-Kaio and Dai-Kaioshin), the owners of Planet Namek.com assumed that the 4 people-1 leader system extended all the way from the Dai-Kaioshin on down. So not only were there 4 Kaioshins under the Dai-Kaioshin, but there were also 4 Dai-Kaios under each Kaioshin, with 4 Kaios under each of them. In total, this gives you 1 Dai-Kaioshin, 4 Kaioshins, 16 Dai-Kaios, and 64 Kaios, for a grand total of 85 Kaio/shins overall, versus the 10 mentioned in the series. And what is it that this horde of gods oversees? PN said that the Dai-Kaioshin ruled over the entire universe, while each Kaioshin ruled a cluster of 4 galaxies, each Dai-Kaio ruled a single galaxy, and each Kaio ruled quarter of a galaxy.
First off, this setup directly contradicts the manga, where North Kaio’s line to the Great Elder can mean that he’s either in charge of 1 galaxy or many galaxies, but not less than 1 galaxy. What's more, Piccolo's explanation of Kaioshin refers to the Dai-Kaio as standing above the 4 Kaios, and the Kaioshin standing above even him. If there were 64 Kaios and 16 Dai-Kaios, you think he'd mention that. I guess it could be argued that, what with no true plural in Japanese and all that jazz, Piccolo's explanation is not necessarily incompatible with the idea of multiple Dai-Kaios, since he doesn't explicitly say there is only one. However, since Piccolo specifies there are 4 Kaios, it'd be bizarre for him not to likewise specify the number of Dai-Kaios if there really were more than one.
This cosmology also gives a total of 16 galaxies grouped into 4 groups of 4, while Toriyama's map of the DB cosmos shows only a simple 4-way split, with no sub-divisions shown or mentioned anywhere. Likewise, Toriyama's map only depicts a single "Dai-Kaio's planet", located directly above Heaven, and only 4 "Kaios' planets" located along the cardinal directions. I suppose the Dai-Kaio's planet (as depicted in the anime at least) could house 15 other Dai-Kaios we never see, but it's hard to believe there are 3 more people hiding out on Kaio's tiny planet. To top it off, none of the god hierarchy charts in the daizenshuu, Son Goku Densetsu, or Super Exciting Guides show anything other than 5 Kaios and 5 Kaioshins, plus Elder Kaioshin (a former East Kaioshin). In short, nothing about PN.com's numerous gods or multiple NSEW divisions is shown or mentioned anywhere in the manga, anime, or guidebooks.
PN’s explanation does try to account for the absence of these other Kaios, galaxies, and galaxy clusters by saying that Boo destroyed virtually all of them. While in the manga and anime Boo is only vaguely said to have destroyed “hundreds of planets”, PN claimed that when Boo killed/absorbed each Kaioshin, he also destroyed their cluster of 4 galaxies, and killed the numerous Kaios in each. Therefore, currently only the East Galaxy Cluster is left, with its 4 Dai-Kaios and 16 Kaios (there’s still no attempt to explain why only ¼ of these individuals are ever mentioned in the series). Of course, nothing about this is said in the series, and Toriyama’s DB world map in no way indicates that 3/4th of the universe has been destroyed, or that there were originally 60 more Kaio planets floating around the afterlife, or…well, you get the idea. On the whole, PN’s system was an interesting cosmology, but it’s just not the way things are in DragonBall.
So given all that, where did PN.com get their ideas? One possible source is DBZ movie 9. The backstory for Bojack there says that the Kaios of the North, South, East, and West combined their power to seal Bojack into a "planet at the end of the galaxy". It's not clear what "galaxy" this would be (though again, it could be "galaxies"), and the 4 Kaios' aren't referred to by any designation other than the cardinal directions. If you only had this to go off of then, it'd be understandable to think that the 4 Kaios rule over the cardinal directions of a single galaxy. What's more, the Funimation dub refers to the Kaios as in charge of "quadrants" rather than galaxies or Areas, which could be taken to refer to quadrants of a single galaxy, but probably only if you already had the idea of the 4 Kaios sharing a galaxy in mind. The Funi dub also confused the issue by originally saying that there used to be 4 Grand Kai (their half-translation of Dai-Kaio), rather than Supreme Kai (their term for Kaioshin). This may have influenced the PN.com folks, though as mentioned their system calls for a total of 16 Dai-Kaios. Finally, the idea of a consistent "1 guy overseeing 4 guys" setup all the way down the Kaio/shins hierarchy is probably just too intuitive for many people despite not being what the series or guidebooks actually portray.