Development
After fans likened Naruto, Sasuke, and Sakura to the three main characters from the Harry Potter fantasy books, Kishimoto noted that both trios began their careers in a classroom, though he added that the similarity was unintentional. During the series's publication, Kishimoto married and had children. This influenced how he viewed Naruto's character. Naruto met his parents and learned of their sacrifices to help him to control the Nine-Tailed Fox inside him so that he could protect their world. As a result, Naruto appreciated his life more and learned that his parents loved him, something the author wanted the character to feel based on his own experience as a father. In the first chapters of the series, Kishimoto did not conceive the idea that Naruto would be the son of Minato Namikaze. However, as time passed on, the manga author made touches to Minato's face shown in the Hokage Mountain in Konoha to make them more similar to Naruto with an emphasis on their spiky hairs. However, to reduce too many similarities, Kushina Uzumaki's character was made to look like Naruto's face.
Out of all the student-teacher relationships Kishimoto has created in the Naruto series, the one between Naruto and Jiraiya is his favorite. Right before Jiraiya's death in his fight against Pain in his last moments, he discovers the origin of Pain's multiple bodies and uses his last forces to send that message as a piece of advice to Naruto so that Naruto could defeat him in his place. This arc was the most difficult one to write; he felt this because Naruto truly forgave his enemy. Instead of having the protagonist kill the enemy he hates, as it happens in other series, Kishimoto found the idea of the two characters interacting and settling their differences more challenging. This had a major impact on the writer, and he decided to have Naruto forgive Sasuke during their final fight in a similar manner as he interacted with Nagato. Kishimoto felt the need to create a story arc that would emphasize the tragedy of wars, leading to the final arc, which would include a war. The principal reason for this was a significant difference between the two main characters, Naruto who had no knowledge of wars, and Sasuke who was a victim of one; his entire clan had been annihilated to avoid a potential civil war. As a result, Kishimoto created Nagato as a war victim who would kill Jiraiya, and act as Naruto's nemesis so he would understand the tragedy that Sasuke had experienced. As a result, Naruto's coming-of-age would have been completed in this arc and the final arc, where Naruto deals with world war and develops a vision of the shinobi world as well as how he should handle the conflict.
In the 2015 film, Boruto: Naruto the Movie, Kishimoto developed Boruto and Naruto's relationship from his relationship with his sons. In portraying the adult Naruto, Kishimoto did not want to make the character give a cool impression in contrast to his younger days as a war hero because Naruto being a strong father figure to Boruto would be too boring for the narrative. Similarly, Chengxi Huang wanted to properly display Naruto's facial expression during this scene, stating that while Naruto has grown up ever since his introduction, his gentle smile was the same. Manga author Mikio Ikemoto claimed the scene in which Naruto helps his son to create a Massive Rasengan was his favorite at the time of drawing Boruto, as across this moment, he had to draw Naruto's past to the point he "felt the weight of NARUTO series and its long history behind it."
Early in the making of the series, Kishimoto had poor faith in the manga as he believed the series was lacking something to become popular. After being recommended by his editor to give the protagonist a rival, Kishimoto wrote Sasuke with influences from Takehiko Inoue's Slam Dunk manga, which was famous for dealing with rivalries. When first introducing Sasuke, Kishimoto wrote him as a rival who never noticed Naruto. However, as the series continued, Naruto became strong enough to finally be recognized by Sasuke as a rival. He also intended for both of them to be brother-like due to the fact that both characters suffered loneliness, something that made the readers relate to them, as he noted through fan letters. By Part I's ending, the bond between Naruto and Sasuke was weakened as a result of their fight but still expected from the time when Sasuke accepted Naruto as an equal. Kishimoto compared Sasuke and Naruto to the concept of yin and yang because of their notable differences. When one of the two progressed, Kishimoto made sure the other did too. During the climax of Part I, Naruto and Sasuke engage in a mortal fight, which was directed by Atsushi Wakabayashi from Pierrot. In an interview, the director claimed that the animation was based on a journey to Lake Mashu from Hokkaido to come up with new ideas. Wakabayashi aimed for the characters to move stilted based on storyboards he made, leading to entertaining sequences. When Naruto became berserk due to the Nine-Tailed Fox's influence, Norio Matsumoto aimed to make Naruto behave like a beast, with Wakabayashi aiming to make Naruto look like an equal to his rival. The staff was inspired by 1970s series, like the boxing series Ashita no Joe, most notably its lead character, Joe Yabuki, who was often seen as an underdog the audience rooted for. However, the team still worked carefully to make the two ninjas be equals without overpowering each other.
Before the serialization began, Kishimoto had decided the ending would feature a fight between Naruto and Sasuke. He wanted the conflict to end with Naruto forgiving Sasuke as he had forgiven Nagato while also aiming it as their final battle in the manga. In regard to the fight, Kishimoto wanted to focus on hand-to-hand combat rather than ninja techniques. Anime staff Chengxi Huang said that for the animated adaptation of this fight, the group worked carefully to depict the action in every scene by showing changes on Naruto and Sasuke's clothes and hair. Huang added he felt fatigued by working so much into this fight due to reaching 70 successive cuts at a time.
The final fight between Naruto and Sasuke was considered one of the biggest challenges by the staff from Pierrot, as it took an entire month to adapt it from the manga. Director Hiroyuki Yamashita elected himself in charge of the battle, which left most of the anime members relieved due to his experience. For the scene, Pierrot received assistance from CyberConnect2, who had already adapted this battle through the fighting game Naruto Shippuden: Ultimate Ninja Storm 4. There was a need to make every movement in the fight look realistic, giving Sasuke a scary look as well as the hair movement to express the idea of both fighters willing to do anything to kill each other, which confused some due to Naruto's wish to avoid this fate. The final clash between Naruto's Rasengan and Sasuke's Chidori moves involved references from other scenes of the series to give the viewer a bigger emotional impact. The staff noted that following this fight, Sasuke's face became calmer despite his initial look, giving room to explore his redemption. A symbolism Kishimoto used in the series finale following the final battle was Naruto returning Sasuke his original bandana, representing how their bonds are tied again and no longer having a reason to kill each other.
Naruto's romantic partner was decided during the early stages of the manga. Since Hinata Hyuga always respected Naruto, even before the series's beginning, even before his academy mentor Iruka Umino, Kishimoto felt they were meant to be. This angered his wife, who wanted Naruto to marry Sakura Haruno. When Sakura was introduced, Kishimoto did not think of her as Naruto's future wife: he saw them as being friends and teammates, although once Hinata had appeared, the author thought of forming a love triangle between the three characters. He later regretted the love triangle as he considered Naruto a fighting series with little focus on romance, and he reiterated that "[i]t was all about Naruto and Hinata getting married from an early stage."
When seeing the staff's work to focus a film on Naruto's relationship with Hinata, The Last: Naruto the Movie, Kishimoto decided to oversee the project. Nevertheless, he enjoyed seeing Naruto and Hinata's romantic scenes that he did not write. In regard to Naruto's rank, which remains as the lowest one, Genin, due to Naruto spending most of his time in Part II fighting and training, Kishimoto decided Naruto would skip the following ranks to become the Hokage, which he felt was appealing. In the making of The Last: Naruto the Movie, Hinata makes a red scarf for Naruto. This was based on something Kishimoto's wife actually once did, which brought laughs to the staff developing the film.
Screenwriter Maruo Kyozuka said that he wanted to depict a love triangle between Naruto, Hinata, and Toneri Otsutsuki in the film. Although Naruto is initially clueless about Hinata's feelings for him, during the film, he begins to acknowledge and respond to them. Hinata's character was also developed in the film, with Kyozuka saying that she had to put aside her feelings for Naruto to accept Toneri's proposal so she could find Hanabi. During this scene, Kyozuka wanted to depict Naruto at his lowest after his rejection by Hinata. He then returned Naruto to his brave self, with the character resolving to continue his mission regardless of the cost. Animator Chengxi Huang, who worked on multiple Naruto series, took a liking to this couple ever since he started working on Naruto Shippuden, often aiming to draw scenes of the two and most notably a scene from the final arc when Hinata slaps Naruto to calm him following the death of Neji Hyuga. In the making of the film, he thanked Kishimoto for accepting to do The Last, where the couple was explored furthermore. He looked at their adult selves as an appealing married couple but had to remove a video he made that received backlash for being inappropriate for the demographic.