The Jobs
Medical-nin
Medical-nin are ninja who specialize in medical treatment and use medical-oriented jutsu to heal others. Becoming a medic-nin requires a great level of intelligence and excellent chakra control, since medic-nin use chakra to heal injuries. Aside from their medical training, their combat training consists mainly of taijutsu skills, with emphasis placed on evading enemy attacks. This is because the death of the medic-nin could result in the death of the team. On dangerous missions, a medic-nin will usually be sent along with the team, to increase the survival rate of that team.
Hunter-nin
Hunter-nin are a special team within Kirigakure's ANBU, given the specific duty of hunting down missing-nin. They kill their target, taking the head as proof, and then completely dispose of the body by using various methods, such as cremation or the summoning of wild carrion crows to devour the corpse. This is done in order to make sure the village secrets which a ninja's body holds -- such as chakra types, herbs eaten, ninjutsu, special medicine, and kekkei genkai -- will not be revealed to outsiders. Hunter-nin are also supposed to destroy the corpse at the very spot the body is lying; it is not to be moved after it is dead. As a requirement, they must possess a thorough and intimate knowledge of human anatomy. Due to their reputation for utterly and completely obliterating the remains of their targets, they are code-named "The Undertaker Squad."
Missing-nin
Missing-nin are ninja who have abandoned their Hidden Village, and as such can include ninja of every rank. These ninja are considered traitors and are hunted down because of the secrets they may hold. Other Hidden Villages would be interested in purchasing this information because it could be useful in gaining an upper hand in battle or obtaining a bloodline limit unique to a village. Villages create special units of hunter-nin to take care of this problem, although it's unlikely that every missing-nin has a team of hunter-nin sent after them.
Courier-nin
Courier-nin are ninja that deliver packages from one point to another. They take on extremely dangerous delivery jobs that others will not; these jobs can even be life threatening in nature. They use smoke to communicate with each other over long distances, and are a very determined group of ninja, taking the "postal motto" to new heights. They never deviate from their goals, and perfectly adhere to rules, regardless of what will happen if their package is delivered. When asked their name, they will use their designation number.
