Itawari Nobu began his life as the son of two villagers in a town in the Land of Fire. Although neither his parents nor any close members of his extended family were ninja, his parents ran a weapon shop, and so, once he was old enough to help run it, he came into contact with many ninja, including those who lived in the village as well as those who passed through. Learning to be something of a salesman, Nobu was able to quickly get on good terms with the ninja, and from hearing of their stories, he eventually became interested in becoming a ninja himself, and began training as a ninja at the age of nine.
During his training, Nobu proved to be a competent, though not outstanding, student. From his experience in the shop, he was quite outgoing and personable, and made friends with many of his fellow students. Though he did not have any particular specialty, Nobu took advantage of his parent's business, and learned to use a wide variety of weapons. By the age of twelve, however, he had found himself to be most suited to the use of wrist-mounted, spring-operated senbon launchers, and devoted himself to learning how to use them to the, even to the exclusion of other weapons (aside from more common items like kunai or shuriken).
By the time he was a full-fledged ninja, Nobu had improved his skill with the senbon launcher, and developed a fighting style to complement it. It was at about this time that Konohagakure was first founded. With Nobu being a ninja and his parents being weapon-sellers, it made sense for them to move to the new village, and they had soon settled and set up shop there within a few months of its founding, when Nobu was fifteen.
Nobu entered the Konoha ninja corps with a fair amount of experience as a ninja, and continued to prove himself capable as he carried out his duties for the village. Shortly after he turned sixteen, Nobu was promoted to chuunin.
For his first mission as a chuunin, Nobu was a part of a team sent to deal with some bandit activity that had been reported near a small village. The team was able to make it to the village and track down the bandits, however, despite reports to the contrary, the bandits turned out to be a group of missing-nin. During the ensuing battle, Nobu found himself in a one-on-one battle with a poison-using ninja. Both Nobu and his team won, but during the fight, Nobu was exposed to several deadly poisons, which quickly began to affect his body. He was quickly rushed back to the village to receive emergency medical treatment, and he clinged to life there for several days.This would be the beginning of a long ordeal for Nobu, and once he was finally in stable condition, his team took him back to Konoha for more treatment, where he would require on and off medical attention for the next year, spending most of his time confined to a bed, and taking various medicines to keep him alive. During this long period of recovery, Nobu's condition was so severe that he had to be treated by the exceptionally skilled doctor and future head of the Medical Corps, Amida Kitai. Seeing each other so frequently, the two eventually became friends. Though he never entirely recovered, Nobu was eventually able to regain most of his strength with Kitai's help, and once again become a ninja.
Naturally, Nobu's skills had greatly atrophied over long months of almost no physical activity, and he spent nearly a year undergoing intense training to regain his abilities. During this time, he once again turned to Kitai for help. After finally reaching the point where he had been before his defeat, he requested to join the ninja corps once more. Once he had demonstrated that he was able to function as well as he had before, Nobu was allowed to re-enlist as a chuunin.
