Regular Forces
The regular forces (正規部隊, Seiki Butai) form the foundation of the village and its shinobi system. The majority of shinobi are a part of these forces and together, either individually or in teams, they perform the majority of the missions the village receives. They are also tasked with the various duties within the organisation, such as training and administrative duties.
When an Academy student graduates, they usually become a part of these forces, assuming the rank of genin. Via various exams and tests, they can be promoted to higher ranks, first to chūnin and jōnin after that. Sometimes, when a shinobi is specialised in a very specific skill, they can assume the rank of tokubetsu jōnin, which is a rank between chūnin and jōnin.
Although the higher-ranking members of the regular forces often perform missions alone, most are done in teams. The most basic team is the one a genin is placed in after graduation. This so-called three-man cell consists of three genin under the guidance of a jōnin commander. These teams are meant to give the new shinobi practical skills, while already being a productive member of the organisation. Usually, strong bonds are cultivated between the members of such a team, lasting their entire lives. Because of these bonds and the fact that working with one's long-time team-mates is usually more efficient, these teams often last even after all members have been promoted to chūnin or higher.
Genin - D Rank
Genin, literally meaning 'low Ninja' are the lowest level of ninja and also the ones that display the most difference in power. When they become genin, ninja start to do their bit for their village's economy – being sent on missions that the village gets paid for. They are typically sent either on D-rank missions, which are almost entirely risk-free jobs of manual labour, or, rarely, on C-rank missions, which are a cut above that and begin to verge on real "ninja" work that have a very low possibility of risk to the ninja involved. They are most commonly promoted via the Chūnin exams but can be promoted by their Kage.
Chūnin - C Rank
Chūnin, literally meaning 'Middle Ninja' are heart of the village, the most common shinobi who are qualified to guide other ninja and lead missions. Chūnin have reached a level of maturity and ability that primarily consists of leadership skills and tactical prowess. Genin who do not have the skills to become chūnin are weeded out in the chūnin exams. Some of them move on to function as Academy teachers and others, serve as team leaders in charge of small teams who need to make decisions and utilise the skills of the shinobi under their command to the maximum effect. Chūnin are typically sent on C-rank or B-rank missions. It is at the rank of Chūnin where skilled shinobi are recruited into the Anbu or other section.
Tokubetsu Jōnin - B Rank
Tokubetsu Jōnin, literally meaning 'Special High Jōnin' are ninja who, rather than all-around jōnin training, have jōnin-level ability in a specific area or skill, much like warrant officers in real-world militaries. They are elite specialists in their areas and are often assigned as subordinates to regular jōnin when their services are needed.
Jōnin - A Rank
Jōnin , literally meaning 'Jōnin ' are generally highly-experienced shinobi with great individual skill who serve as military captains. They are the elite of the village and are often sent on A-rank missions, an experienced Jōnin may even be sent on S-rank missions. It is not unusual for jōnin to go on missions alone.
When a ninja becomes a jōnin, they may be assigned a three-man genin team to supervise. One part of their duties is to help instruct and train these genin to become competent ninja. They carry a lot of weight as a group and are the deciding factor in choosing a Kage.
Kage - S Rank
Kage, literally meaning 'Shadow' are the pillar of the village. They are often but not always the most skilled shinobi within their respective village. They can be selected for many reasons, Wisdom, Skill, Experience. Only the leaders of hidden villages of the Five Great Shinobi Countries are referred to as such. The Kage oversee the activities of their villages, from sending ninja teams out on their missions to making the hard decisions regarding the safety of their people.
Once a ninja is made Kage, normally by a predecessor, the title remains with that person for the rest of his or her life. While the previous Kage may retire, he may resume his role as leader if his successor dies. In the event that a Kage dies without naming a successor, an ideal heir could find a more suitable successor. A Daimyō has the authority to name a candidate Kage to serve as acting leader but they cannot be elected Kage without the support of the Jōnin .
Divisions
Aside from the Regular forces, there are a number of Factions within a village that have their own purposes and objectives, some of which are controlled by the Kage alone. While there are common groups within a village, each village often has their own specialised divisions which vary greatly from each other, depending on the focus of the village in question.
Anbu
Anbu, literally meaning 'Dark Side' which is short for Ansatsu Senjutsu Tokushu Butai 'Special Assassination and Tactical Squad' take orders directly from the Kage, performing special high-level missions, such as assassinations and torture. The ANBU usually work in teams formed to the requirements of the mission, ensuring maximum success. The shinobi in the ANBU are hand-picked by the Kage; chosen for their individual capabilities and special skills. Age, gender, background, or previous rank bear no weight in this decision but are chosen only chosen once they have graduated from Genin. Members can also leave the organisation and return to the regular forces. They wear their mask even in their own village, for their identity as an ANBU agent is to be known only by the Kage, Jōnin Hanchou and Anbu Captain though while it is not expected of them, many Anbu reveal their identities to each other during their time as team mates. When they are not on Anbu duty they act as regular shinobi but rarely have teams. Anbu often take non consequential roles within the village so their absence while on missions does not negatively affect the Village and so people do not notice their absence often.
There are apparently no true ranks within the ANBU, unlike within the regular forces. Once a person becomes Anbu they are referred to as Anbu. Team leadership and hierarchy seem to be based on merit and experience. The leaders of the teams are called squad leaders (分隊長, Buntaichō), a position held in high regard.
Medical Teams
The medical teams (医療班, Iryō-han) is the supporting side of the shinobi forces and consist of shinobi of any rank. They consist of medical-nin, working behind the scenes to heal sick and injured shinobi and to make sure the organisation's resources are always in peak condition. Medical-nin are similar to a Hospital Corpsman or HM of the military in real life. They also do extensive research into new techniques, medicines, diseases and the human body. Although not seen very often, they are highly respected. Even to a Jōnin, the advanced skills of these shinobi seem like magic.
Not all medical-nin are members of the medical teams, though. There are also medical-nin within the regular forces, who go along on standard missions to increase the success-rate referred to as field medical-nin. Though medical-nin from the hospital are sent out into the fields from time to time. However, back in the village, it is the medical teams who run the hospital and treat the wounded.
Key Positions
Within every village lay key positions besides Kage. These positions are filled by the very best in their respective fields and are chosen as vigilantly as a Kage would be selected and are often appointed by the Kage personally. The people within these positions are often seen as the leaders of their Village, the most trusted and wise of the Villages Shinobi. They act as the pillars of the Village and will often act as advisor's to the Kage.
Jōnin Hanchō
The Jōnin Hanchō is often viewed as the Leader of the regular forces, the best the Village has to offer besides the Kage. As a representative of the regular shinobi forces, they are a member of the council, giving them a say in important matters such as choosing a new Hokage. They are the highest-ranking normal shinobi in the village, but still officially a Jōnin themselves. Unlike many positions the Jōnin Hanchō his not selected by the Kage, while the Kage can make a request for a certain person to become Hanchō, it is ultimately up to the Jōnin to choose who will represent them and the regular shinobi within the village..
Anbu Taicho
The leader of the Anbu, this is a very prestigious position within the Anbu as it is the penultimate position within the division and many Anbu do not live to gain the experience or respect needed to gain such a position. The Anbu captain is selected by the Kage themselves and oversee the operations of the division. They often give daily reports to the Kage on the going on's and will take high ranking missions themselves quite often.
Whenever the Kage leaves the village, the Anbu captain will act as a personal guard of their leader. They operate as most Anbu, they hold an inconsequential position within the leaf so they can leave on covert missions without arousing suspicion. The Anbu captains identity is only known by the Kage and whoever the Leader wishes to know.
Head Medic
This is the leader of the medical squads within a village. They are often the most skilled medical shinobi and are respected by their peers. They organise the Medical Squads when in combat and run the hospital when they are not needed for any combat position.
While they may be a regular shinobi, more often than not the Head Medic is someone who has focused their entire lives solely on healing.
Security Head
A very important position within the village, and often overlooked by many. The security heads mission is to protect the village against threads from the inside and make sure that it has not been breached. They often search for spies within the walls, or act as almost like a police commissioner.
They handle the day to day security of the village, making sure that there has been no secret incursions. They are extremely vigilant in this role and are often just a regular Jōnin.
