Sasuke would be extremely angry. He and Naruto had a complex relationship that evolved from rivalry to friendship. His first reaction would likely be to seek vengeance. Kakashi himself would be filled with guilt and self - loathing. He has always been Naruto's teacher and protector in a sense. Hinata would be heartbroken. She had deep feelings for Naruto. The rest of the village would be in shock and disbelief. Naruto was seen as their future, and his sudden death at Kakashi's hands would create a sense of despair and confusion.
Jiraiya would be in a state of extreme sorrow. He saw Naruto as his successor and a great hope for the future. His grief could turn into a determination to find out what went wrong and make Kakashi pay if he thought there was any foul play. The Akatsuki members might be initially surprised but then see an opportunity. Without Naruto, the balance of power in the ninja world could shift. And characters like Gaara, who had a connection with Naruto after their own battles and mutual understanding, would be in disbelief and feel a great sense of loss.
Perhaps there is a situation where Sakura is trying to protect Naruto from a dangerous attack, but due to some unforeseen circumstances, like a misdirected healing jutsu turning into a harmful one, she ends up killing him. It could then lead to a story of guilt, revenge, and the search for a way to bring Naruto back.
One possible motive could be mind control. Maybe an enemy manages to take over Kakashi's mind and forces him to harm Naruto. Another could be a misunderstanding. For example, if Naruto was thought to be possessed by a powerful and dangerous entity that Kakashi believed could only be stopped by killing Naruto.
Sakura would probably be shocked. She knew the Akatsuki was powerful, and Naruto killing them all might make her see Naruto in a whole new light, perhaps as a more dangerous or powerful figure than she initially thought. Kakashi, on the other hand, might be worried about the implications. He would be proud of Naruto's strength but also concerned about the power vacuum and how it could affect the balance of the ninja world.
Kakashi could be initially shocked. He might not have expected Naruto to have such feelings towards him. But being Kakashi, he would probably handle it in a calm and collected manner.
Another motive might be related to some dark power corrupting Team 7. This power could have twisted their minds and made them see Kakashi as an obstacle in their path to achieving ultimate power. It could be something like the curse mark in the original Naruto series but even more powerful and insidious.
Sasuke would likely be filled with rage. He and Naruto had a complex relationship, and Naruto's death at Sakura's hands would make Sasuke seek revenge or at least demand answers. Kakashi, on the other hand, would be deeply saddened. He was Naruto's teacher and would probably feel a sense of failure.
Surprise. They might be surprised to see how fans imagine different scenarios for them. For example, a character from a magical girl anime might be shocked to find a fanfiction where she's suddenly a detective in a noir - style story.
Kakashi provides a sense of stability. Naruto has a somewhat chaotic life, but Kakashi is a constant presence. He's like a father figure in a way. He's always there when Naruto needs advice or just someone to be around. This stability helps Naruto feel more secure and less alone in his journey as a ninja.
Naruto could also be a bit angry at first. Angry that she had been away from him all this time. But then that anger would quickly turn into overwhelming love and relief. He would have so many questions to ask her about why she wasn't there as he was growing up, but at the same time, he would be so glad to have her there now.
Hinata would be heartbroken. She loves Naruto deeply. Her world would shatter. She might try to find out the truth behind his death, not believing that his friends could do such a thing without a good reason. And she would probably hold a grudge against those involved.