Naruto has a large and colorful cast of characters, running a gamut of detailed histories and complex personalities, and allowing many of them their fair share in the spotlight; they are also seen to grow and mature with the series, as it spans several years. As fitting for a coming-of-age saga, Naruto's world constantly expands and thickens, and his social relations are no exception – during his introduction he has only his teacher and the village's leader for sympathetic figures, but as the story progresses, more and more people become a part of his story.
The students at the Ninja Academy, where the story begins, are split up into squads of three after their graduation and become Genin, junior ninja. Each squad is assigned an experienced sensei. These core squads form a basis for the characters' interactions later in the series, where characters are chosen for missions for their team's strength and complementary skills; Naruto's squad 7 becomes the social frame where Naruto is acquainted with Sasuke Uchiha and Sakura Haruno, and their sensei Kakashi Hatake, forming the core of his world-in-the-making. The other three-man teams of his former classmates form another such layer, as Naruto connects with them to various degrees, learning of their motives, vulnerabilities, and aspirations, often relating them to his own. The groups of three are not limited to the comrades Naruto's age – groups in the story in general come in threes and multiples of three with very few exceptions.
Sensei-student relationships play a significant role in the series; Naruto has a number of mentors with whom he trains and learns, most notably Iruka Umino, the first ninja to recognize Naruto's existence, Kakashi Hatake, his team leader, and Jiraiya, and there are often running threads of tradition and tutelage binding together several generations. These role models provide guidance for their students not only in the ninja arts but also in a number of Japanese aesthetics and philosophical ideals. Techniques, ideals, and mentalities noticeably run in families, Naruto often being exposed to the abilities and traditions of generation-old clans in his village when friends from his own age group demonstrate them, or even achieve improvements of their own; it is poignantly noted that Naruto's generation is particularly talented.
Character names often borrow from Japanese folklore and literature (such as the names borrowed from the folktale Jiraiya Goketsu Monogatari), or are otherwise elaborate puns; often there is a noticeable influence of the story behind the name shouldered by the character.