Theories on Summoning by Jiraiya, Gama Sannin
Before a summon can be performed, a prospective summoner must first sign a contract with a given species. The contract can come in the form of a scroll or a tattoo. The summoner then signs the contract in their own blood. After this, they need only perform the hand seals, offer an additional donation of blood, and use the same hand they signed the contract with to summon the creature. The amount of chakra used during the summoning determines how big the summoned creature can be. It should be noted that anyone can summon the animal as long as they have the blood from someone who has made a contract, along with sufficient chakra of their own.
When an animal is summoned it is transported from its place of residence to the summoner's location. Once summoned, the animal can perform a task or help the user in battle. The summon is not required to help the user, and may be more of a hindrance than an ally. In addition, summons are able to summon their summoner. They may also wear a forehead protector, suggesting a loyalty to only one village.
While most summoners have only been shown capable of summoning one type of creature, it is thought to be possible to be able to summon several different animal types and even people. So far, only Minato-kun has been able to summon a person, albeit himself, after taking the ability of a summon to "reverse-summon" its human summoner, and combining it with a number of seals and seal-techniques. His implement to use the techniques are inscribed with a blood seal so only he can use it, as well as a blood seal being used in the security seals, so that it cannot be broken down and studied.
Summoning can serve as a base for other jutsu, as is the case with Summoning: Food Cart Destroyer Technique or Summoning: Toad Shop Technique, with which I summon a toad and then perform a jutsu or collaboration jutsu. In these cases, summoning may not be restricted to creatures, as my teammate Orochimaru can not only summon snakes, but also defensive gates to protect himself. Items can also be "summoned" from scrolls. Because the items are not summoned from anywhere, instead only being released from storage, no blood is needed and thus it is not a conventional summoning. If a user attempts to summon an animal without first signing a contract, the user will be teleported to the home of the animal they have a natural affinity for. I know this, for Orochimaru attempted to summon an animal of some sort, and wound up in the natural homeland of the snake summons. He attempted this after I myself gained the help of the Toads, and recited the tale upon his return.
The animal you have a natural affinity for can change until you reach the age of 21, by which point the animal that your inner self resembles most will be that of your natural affinity. Should you sign a summoning contract before this age, you shall immediately certify your natural affinity to be that of the animal of the contract. After the age of 21, if you attempt to sign a summon contract, upon your first attempt at summoning, the guardian summon of the contract of your chosen animal shall appear, allowing you to sign that contract instead. Your name is then stricken from the contract you first signed by the summon boss, unless you are one of the privileged few allowed to hold multiple contracts.
Although all shinobi have the ability to summon, and many summons can exist, full-blown clans of summons are few and far between. Similar to how for every Hyuga or Uchiha shinobi in the village, there are dozens of civilian or clanless shinobi; summon clans are often the name given to truly large groups of summons of a particular species. The only well-known summon clans are as follows: the Toads; the Slugs; the Snakes; the Apes (though unlike most other clans, they are further splintered. Hiruzen-sensei has cultivated a special relationship with Enma, the first and present boss-summon, allowing him to summon all sorts of apes. Otherwise, he'd only be able to summon the one part-clan species he was closest to. This is the first time in recorded history of summoning, for the Ape Clan are a first generation clan); the Leopards; and finally the Moles. All other summons are either lone summons, small summon families or brand new summon species. Co-incidently, four of these six well-known contracts have present ties to Konoha, and the Moles were once summoned by a Hyuga.
I have asked Fukasaku-sensei how to create a summon species, and was told that a number of things must happen. Firstly, you must take a regular animal and live with it for at least a year. Then, you must tribute some of your chakra to the animal. The amount you transmit will allow it to adapt accordingly: the more chakra tributed, the further the animal changes, whether this be in size, strength, or ability. A simple "grunt" summon requires the same amount of chakra as that to summon seven basic Bunshin. An average boss summon would require the same amount as a chakra-costly A or B – ranked jutsu. A true boss summon would require about two A-Rank chakra-costly jutsus worth, or a single S-ranks worth of chakra. This is because your mind has to think about the changes it wants, though only fairly basic ones shall occur. Thoughts such as "colour; size; shape; ability" will allow it to adapt, and some description can be put in, but something incredibly complex such as an exact mass or size, a particular colour scheme which needs about five or more shades or colours, etc. would simply be too difficult to achieve. The reason so much chakra is needed to "create" a boss-level summon is that although the summon can still increase their chakra reserves, the initial chakra boost is transferred to their reserves as well as granting them intelligence similar to that of an average human.
Most shinobi will never summon an animal, as there are not enough summon clans in the world. Many summon partners are personal summons of either a person or a clan. This is why such men as Sanshōuo no Hanzō have massive summons that no-one can pinpoint to another in history before them – the summon itself is personal and exclusive to that one person or clan. Because out of every 100 shinobi, 37 shall remain Genin for their entire life-span, of which most will be in the reserves; 36 shall make only Chūnin, of which only 17 shall be on the front-lines, the rest in other areas of shinobi expertise; 10 shall make Tokubetsu Jōnin, of which only 3 shall remain in combat-intensive areas; 14 shall make Jōnin, almost all of which will be in combat-intensive areas; and 3 shall make Kage level. Due to this, only the top 15 of these shinobi shall be able to summon, either due to finding a contract or creating a new one. All the Kage-level shinobi shall be able to, as well as the top twelve shinobi (not including the Kage-level) of the Tokubetsu Jōnin and Jōnin levels.
Interestingly enough, a summon clan will only ally with a single person, and it shall not matter if they are a member of a clan at any particular point in time, the summons will not allow their clan to ally with the summoner's clan. However, a summon clan may allow a child of a present or previous summoner to immediately summon them, the contract being a mere item to finalise this development. This happens sparingly. Also, summon clans will only have one master and one apprentice summoner at any point in time, the summoner with the senior amount of time summoning being seen as the master. In the rare case of the summoner with the least time being a far better summoner, they are then declared the master of the contract. If this becomes the case, the other summoner can remain a summoner, though their ability to allow others to sign the contract becomes withheld. In the even rarer case of both summoners being considered masters of the contract, then both members may take a single apprentice summoner, though then the case of the better summoner of the apprentices shall become the master of the contract once both masters pass on or up the contract.
Every summoner has a personal summon or two, even if they can summon an entire clan. My own personal summons are Gamabunta and Gamaken, the two brothers; Minato-kun's personal summon is Gamasuto, a medium-sized toad (comparable to Gama), who carries dozens of regular-sized tri-bladed kunai and two large versions of these, which is where he got the idea for them; Tsunade-hime's personal summon is Katsuya; Orochimaru's is Manda; Hiruzen-Sensei's is Enma; Hanzō's is the huge salamander he summoned to fight off we Sannin; and I believe that Inuzuka Tsume's is also her familiar Kuromaru, who is an example of a summon raised from being a simple ninken.
Above the rank of summon boss are other ranks in certain families or clans, as well as certain personal summons. The most obvious and well-known case is Hanzō's huge salamander, who is way above the rank of a "summon boss". All other ranks are unofficial, but members of certain clans such as Fukasaku and Ma, as well as the Ōgama Sennin, are considered stronger than Gamabunta, even though 'Bunta is the boss of the contract. This is due in part to the fact that they have "evolved" passed the status of Summon Boss, growing with strength after long relations with a previous summoner. Again, this is linked to personal summons – only through the status of a personal summon do summons evolve, otherwise they remain small and weak in stature. Gamakichi and Gamatatsu have been around for about seven years, but have practically remained the same size due to them not being connected to a summoner in any remote manner.
It is up to the boss summons of each contract that an act will affect to decide whether or not an additional summon contract can be signed, if both contracts are summon clans, whether they be well-known or newly created. If one clan has no boss summon, either through the death of the previous boss or the lack of one, then the boss summon(s) of the other contracts will decide what happens. If all the summon clans available for this to affect have no boss summon, then the summoner may summon as many contracts as they wish provided none have a boss-summon. If one summon boss disagrees, then either the old contract between summons and summoner is rendered finished, or the new summons will simply not allow the summoner to call upon their services. If a clan is newly created, then they are immediately bound to their summoners will, as the boss-summon has not yet taken true steps to independence. Summon clans are registered by the amount of summons that take the chakra usage of a basic C-Rank jutsu or more, of which there must be at least 20. Contracts with less members of this requirement are not clans, and are not subject to the rules, though particularly strong or foolhardy bosses take part anyway.
Summoners should generally respect their summons, as the summons are often stronger, more experienced and in general better fighters than their summoners. Of all the summoners I've faced, with is a fair few over the years from all areas, only Orochimaru demands respect rather than gives it, though his dominance of the Snake clan is needed for they, like him, need the person above them to wield power to hold them in line.
Despite the fact that more and more summoners prefer to summon larger summons, myself included in that particular list, it still remains a fact that the best summons are smaller, faster and stealthier than large summons like the toads. I have seen a small contract with which the user summoned herons of various shapes and sizes, though all of them where of average size or smaller due to the control of chakra during the time they were raised. Although this was the case, they were faster than most carrier nin-birds, and were used as deadly eliminators of plans via the airways, the fastest way of informing superiors of critical information. They were also used as carrier nin-birds by their summoner, and even ended up giving them a nickname which was used in the Bingo Book – "The Swift Feather" – showing their strength in summoning and speed in a quick manner.
There are three shinobi who are the most well-known summoners by other summoners. One of them is in fact the man known as "Kami no Shinobi", Hiruzen-sensei, who possesses a small self-created summon clan which are of the apes. He is also renowned for having the only S-Ranked Summon who is both average size and can perform shinobi techniques. Hiruzen-sensei is unique in recent years for his immediate creation and subsequent use of a now renowned summon clan, as well as having the sense to utilise the appearance of the apes in order to allow them to perform hand-seals, circumventing the old issue with summons finding it difficult to control their chakra.
The second man is Sanshōuo no Hanzō, who is world renowned for his monstrous salamander companion, and known only in summoner circles for the even greater achievement of the absolute mastery of contract creation, having created a grand total of one major summon clan, which is currently unknown for it has never been used; three large summon families; eight small summon families; and about twenty to thirty personal summons. Many of these have been given out to other people, including a possum family, three types of bird families and a number of different amphibian personal summons. He is known as a kind man for these actions, and throws many celebrations which are exclusive for summon-nins. This means that only one of the five Kage are ever invited, and Konoha has the largest number of seats from the villages of the Gokage, with Kusagakure and Takigakure having the most seats overall.
Finally, the most famous summoner of all time is known simply as "Kami no Kuchiyose", and was famous for using multiple summons in battle at any one time, all of which raised solely by himself and then combined into a massive summon contract. Though it is thought to be the size of the summon clans, it isn't a clan itself, for it possesses many summons of different species. He is not the first person to summon, nor the one who created the first true contract, but the only ninja who managed to create a multi-specie contract, as well as a contract with every summon being "boss" level.
Ironically enough, though only the top shinobi can summon, this is due to the fact that they learnt while Genin-standard, growing up summoning and the nature of every summon is to be competitive with others, so naturally they were encouraged to continue that tradition, rising to the highest points in the shinobi ladder in that village. Very few people are the exception to the rule, and therefore many contract holders take their apprentices before or very shortly after the graduate as Genin.
Very few summoners make ANBU. Due to the fact that ANBU are supposed to be the Black-Ops, anything which shows a particular resemblance to a well-known shinobi should not be attempted, but many summoners will not be able to hold back. The only ANBU-summoner I have ever met was Orochimaru, and this is only due to his fascination with jutsu of all natures which allowed him to make do without his summon skills, which even then cut his abilities by a lot. Similarly, many would be ANBU like to choose their masks with something in mind, such as the summon animal they use or would use, or another iconic design. Orochimaru was designated "Jakkaru" or Jackal, because it misled opponents, before his mask became well-known. He then traded it with another "well-known" ANBU, becoming "Raion" or Lion, and then after a two-year stint in ANBU, Orochimaru was drafted back into the Jonin ranks.
In fact, summoners have their own ranking system, ranging from student to Kami no Kuchiyose, with seven ranks in total. Student is the equivalent of an E-Rank; Junior is the equivalent of D-Rank; Adept is C-Rank; Journeyman is B-Rank; Lord is A-Rank; Master is S-Rank and Kami no Kuchiyose is SS-Rank. To date, only one nin has made SS-Rank, hence the title, and he was specialised summon-nin.
Summon-nin are ninjas who specialise in summoning techniques and techniques related to summoning. Orochimaru and myself are both summon-nin, though he is considered a Ninjutsu specialist and myself a Fuinjutsu specialist. This is because our skills often are dictated by our summoning abilites – I developed my sealing talent while staying with the toads, my taijutsu is known as Toad Sage Fist is due to it being taught to me by the toads, and many of my ninjutsu talents opened up while training with Gamabunta. Orochimaru meanwhile has developed dozens of ninjutsu, most of which use his snake summons as a basis; he has gained the Kusanagi from the snakes, and even now he acts snake-like on a regular basis. Tsunade is once again the odd one out in the Densetsu no Sannin, for she is the only female ninja in the trio, the only medic, the only Taijutsu specialist, and she gained her contract after learning all these talents, whereas Orochimaru and myself gained them during or only after we gained our respective contracts.
Without a doubt, summon-nin are among the most dangerous fighters you can come up against due to the sheer variety of types. Whereas with Ninjutsu specialists you simply need to know what element their chakra is in order to form a counter, albeit a temporary one, and with Taijutsu almost all baring the Gentle Fist need true bodily contact, meaning certain abilities to neutralise contact will make it similarly useless for a while, summoners can have many different summons available to them, and even Student-level summoners who are C-Ranked as shinobi can eke out victory against a much stronger, more experienced shinobi due to having a summon to help them out. This is an extreme example, but summon-nin are among the worst enemies for people to face.