Genin (下忍, Literally meaning: low ninja, Meaning (Viz): junior 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. When Konohagakure was short-handed on upper-level ninja because of the invasion, the village had to occasionally send genin on higher-ranked missions.
Genin are put in four-man cells, or squad, consisting of three genin and a jōnin-sensei, in order to learn teamwork and experience true ninja life under the supervision and protection of an elite shinobi. The make-up of these teams is based on the individual skills of the genin, so that there will be a balance between the teams. For instance, Naruto Uzumaki, who passed with the lowest grades, was put in a team with Sasuke Uchiha and Sakura Haruno, who passed with the highest grades and highest written exam scores, respectively. Due to the fact that genin are the lowest level ninja, they are normally assigned D-rank or C-rank missions so as to gain experience before taking on harder missions or being promoted to the rank of chūnin, by successfully completing the Chūnin Exams, a set of difficult tasks made to test the skills of genin to see whether or not they are fit to become chūnin.
- A shinobi's rank doesn't necessarily reflect their abilities. Some shinobi such as, Sasuke and Naruto, left Konoha to train with a Sannin and, despite being genin, were much more capable than most chūnin and jōnin. Although Sasuke was never promoted above genin, he became one of the most powerful shinobi of his time.
- Similarly, Kosuke Maruboshi, who is called the Eternal Genin (万年下忍, Mannen Genin) has the skills of a jōnin-level shinobi, but is officially a genin — a rank he had consciously decided to remain at, due to personal reasons. He shares the epithet with Might Duy, who in his twenty years as a genin mastered the Eight Gates.