One possible plot could be that a strange jutsu backfires on Sakura during a mission. This jutsu could be an experimental one that an enemy ninja uses. As a result, Sakura turns into a little girl. Naruto, being her friend, has to protect her in this vulnerable state. He might have to teach her basic ninja skills all over again as she has the mind and abilities of a little girl now.
If Sakura turns into a little girl in the fanfiction, her relationship with Naruto would be very different. Naruto would probably take on a more dominant role in their friendship. He'd be the one making decisions for her and guiding her. Her relationship with her rivals might also change. For example, other female ninjas who were once her competitors might now see her as less of a threat in her little - girl form and might even try to befriend her. And her relationship with her sensei, Kakashi, would be more like a student - teacher relationship where he has to teach her from the very basics again, which would create a different dynamic compared to their previous relationship.
Naruto would definitely have a huge character development. At first, he might be confused and a bit frustrated about the change. But as time goes on, he could learn to embrace his new form. He might become more empathetic towards the female characters in the village, understanding the challenges they face. Sakura, on the other hand, would feel guilty for the accidental transformation. She would strive to find a way to turn Naruto back, which could lead to her developing her medical ninjutsu skills further.
One possible scenario in this fanfiction could be that Naruto uses some sort of jutsu accidentally. Maybe he was trying out a new technique and it misfired, turning Kiba into a girl. In fanfiction, this could lead to a lot of humorous situations. For example, Kiba, now as a girl, might struggle with how to act or how to deal with the reactions of his friends like Shino and Akamaru. Also, Naruto would likely feel really guilty and try to find a way to reverse the transformation as soon as possible.
He might become more sensitive. Naruto as a boy was always bold and brash, but as a little girl, he could be more in touch with his emotions. He may cry more easily or be more empathetic towards others.
The plot of a Naruto turns into Sakura fanfiction could involve Naruto experiencing Sakura's emotions more directly. He might feel the pressure she has always felt to keep up with Naruto and Sasuke. This could lead to him understanding her better and trying to change things when he turns back. Also, there could be a situation where Naruto - as - Sakura has to go on a mission alone. This would force him to fully embrace Sakura's skills and personality. He could end up using her intelligence and strategic thinking in ways he never thought possible, which would not only be a growth for the 'Naruto - in - Sakura' character but also an interesting exploration of Sakura's potential.
The storyline would be greatly affected. In terms of character development, Naruto would have to learn a lot about Sakura, her insecurities, and her strengths. This new understanding could then be carried over when he turns back to his normal self. In the plot, it could also lead to new alliances or enemies. For example, if Naruto - as - Sakura accidentally offends someone who Sakura had a delicate relationship with, it could create new conflicts. Or, on the other hand, he could make new friends by showing a different side of Sakura that others hadn't seen before.
Sasuke is a very common character paired with 'girl Naruto'. Their relationship, which was already complex when Naruto was a boy, becomes even more so in these fanfictions. There's often a lot of tension and unspoken feelings between them. Another common pairing is with Naruto and Kakashi. In some stories, Kakashi becomes a mentor in a different way to 'girl Naruto', guiding her through the new challenges she faces as a female ninja.
Naruto would probably be very friendly and kind. He has a big heart, so he'd likely greet her with a big smile and start chatting right away, asking her name and where she's from.
One possible plot is that Naruto, now a girl, enters a yuri - themed ninja tournament. There, she meets a powerful and beautiful female ninja. They start off as rivals but as they face each other in battles and training sessions, their relationship evolves into something more. Naruto's new - found femininity could add a whole new dynamic to their interactions.