These characters are all a part of the "Konoha Rookie Twelve" that came of age in the years following the defeat of the Kyuubi. They are all around 12 when the series begins, and all go on to become crucial characters in the plot of the story, which has so far taken place in the space of four years.The Konoha Rookie Twelve consists of four different squads, each with a leader. These squads were formed directly after Genin graduation.
Each character has a personal history, as well as a history withing the current events of the Naruto storyline. Their personal histories all tie back to the events of the Kyuubi attack twelve years prior, although they all grew up under vastly differing circumstances.
Team 7:
Genin: Naruto Uzumaki, Sakura Haruno, Sasuke Uchiha
Lead by: Hatake Kakashi
This team is the centerpiece of the first season of the show, and introduces viewers to the main protagonist and later antagonist of the series: Naruto Uzumaki, and Sasuke Uchiha. Naruto Uzumaki grew up as a troubled child, as he has the nine-tailed Kyuubi demon sealed inside him. The demon had attacked Konoha right before his birth, and had killed many. The Fourth Hokage saved the village by sealing the demon inside the newborn Naruto, and while he was never aware of this, many townspeople shunned him because they believed him to be inherently evil.
Sasuke Uchiha also had a very troubled childhood, from the time when his older brother went on a killing spree and killed every member of the Uchiha clan, save for Sasuke, for no apparent reason. Sasuke ended up joining Team 7 after graduating from ninja school as a Genin, but later left to pursue revenge against his brother.
Sakura Haruno is a female ninja that joined Team 7 because she wanted to get closer to Sasuke. However, she soon realizes that Sasuke does not have time for her as his revenge against his brother is the only thing that motivates him. She often acts ditzy or silly, but showcases her aptitude for the field of medical ninjutsu later in the series.
Hatake Kakashi is one of the most respected ninja in Konoha. He is known as the "copy ninja" because of his special sharingan eye, which he can use to copy opponent's precise moves. He has a cool and aloof attitude and is frequently the voice of reason within the squad.
Team Guy:
Genin: Rock Lee, Neji Hyuga, Tenten
Lead by: Mighto Guy
Rock Lee is the only ninja in Konoha who is not able to use Genjutsu (illusionary arts). As such he is forced to rely on his amazing taijustsu, or fighting skills. He credits the team leader, Guy, with inspiring him to fulfill his lifelong dream to become a ninja, even though he did not have talent at an early age. He tries his best to emulate Guy, and even cuts his hair and dresses the same way.
Neji Hyuga is part of the aristocratic Hyuga clan, but was shunned as a part of the "branch" household at an early age, despite showing great natural talent. His greatest rival is Hinata Hyuga of Team 8, who is a member of the "main" household.
Tenten is a weapons specialist ninja, and not much is known about her backstory. She is the only ninja not to recieve a flashback episode during the Chuunin exam.
Mighto Guy is the leader of the team and is known for his enthusasm and over-the-top personality. He also has a bitter rivalry with Team 7 leader Kakashi, which Kakashi denies even exists (much to Guy's chagrin)
Team 8:
Genin: Kiba Inuzuka, Shino Aburame, Hinata Hyuga
Lead by: Kurenai Yuhi
Kiba Inuzuka comes from a long line of animal trainers. He is never seen without his dog, Akimaru, who is his partner in combat.
Shino is also an animal manipulator, but he uses a certain breed of insect to do his bidding. He has a symbiotic relationship with insects that live inside his trenchcoat.
Hinata is a member of the "main branch" of the Hyuga clan, and as such was expected to develop a strong talent for ninjutsu. However, her soft-spoken mannerisms and shy demeanor always prevented her from getting the respect of her family.
Kurenai is the only female team leader, and is a self-described tomboy. She tries to counsel Hinata, who never knew her father, and forms a special relationship with her.
Team 10:
Genin: Shikamaru Nara, Chouji Akimitchi, Ino Yamanaka
Lead by: Asuma Sarutobi
Shikamaru is one of the strongest Genin in Konoha early on because of his tactical thinking and cool head. Although many perceive him to be disinterested in his comrades, he tries to free himself from emotions so he can keep his head level in battle. He is the only ninja to pass the first Chuunin exam.
Chouji comes from a powerful warrior family that is able to use special foods to gain chakra. Chouki is never seen without his potato chip bag, and often waits until the last minute to get involved in battle.
Ino is a female ninja who has a firey temper and a big rivalry with fellow female ninja, Sakura. She often conceals her emotions from her comrades and gives off a very cool attitude towards those who first meet her.
Asuma is the leader of the group and, like Shikamaru, is very laid back and tactics-oriented. He often plays chess with his students and emphasizes strategy in all of his lessons.
Each Ninja squad is assigned missions on a sliding "A-D" rank scale. Occasionally, ninja squads will branch out on their own to complete non Hokage-sanctioned missions. This is most evident when Team 7 goes out to look for Sasuke once he leaves Konoha.
The different Naruto character squads have already played a major role in the plot of the story, and represent many different feelings within the Konoha village. Although it has not been hinted that they will become direct rivals, many of the squads will evolve and change to represent conflicting ideas about the future of the Konoha village.