Sakura would be heartbroken. She had grown up with Naruto and always saw his potential. His death would make her question a lot of things. She might become more withdrawn and serious, vowing to become stronger in Naruto's memory. Kakashi would be deeply saddened as well. He had trained Naruto and seen his growth. He would likely feel responsible in some way too, as he was one of Naruto's teachers. As for Hinata, she would be shattered. She had deep feelings for Naruto, and his death would be almost unbearable for her. She might become more determined to protect the village in Naruto's name.
Iruka would be devastated. He was one of the first people to truly believe in Naruto. His reaction would be a mix of sorrow and anger towards Jiraiya. Tsunade would be in a difficult position. As the Hokage, she would have to deal with the political fallout of Naruto's death. And she would also have to console Jiraiya, who was her old teammate. The other ninja teams in the village would be affected too. They had all interacted with Naruto at some point, and his sudden death would make them more cautious and also more determined to protect each other, as they had seen how quickly life could be taken away.
Jiraiya himself would be completely broken. He was Naruto's mentor and had high hopes for him. His actions would likely make him an outcast in the village. Also, the Nine - Tails within Naruto would be a major factor. Its power might go out of control or be lost forever, which could have unforeseen consequences for the balance of power in the Naruto universe.
One possible plot could be that during a very intense and dangerous training session, Jiraiya attempts a new and powerful jutsu. Naruto, being eager to learn and prove himself, jumps in too soon to assist or observe closely. Jiraiya loses control of the jutsu slightly and it accidentally hits Naruto, leading to his death. This would then cause a huge upheaval in the ninja world. All of Naruto's friends and allies would be in shock and disbelief. Sasuke might be filled with rage and vow to seek revenge, not fully understanding it was an accident at first. And Jiraiya himself would be consumed by guilt, perhaps even going into a self - imposed exile as he couldn't bear to face the consequences of what he had done.
Naruto would be determined to get to the bottom of it. He would not just accept the betrayal at face value. He would use his skills and the help of his friends to investigate what made Jiraiya turn against him. Naruto's ninja way is about never giving up, and this situation would be no different. He would fight against this betrayal, both physically if Jiraiya became an enemy in combat, and emotionally, trying to understand the reasons behind it all while still holding on to the hope that Jiraiya could be redeemed.
He would probably also feel angry. After all, he has sacrificed so much for the village and for them. He might start to question his own beliefs and values. But Naruto being Naruto, he would not give up easily. He would try to prove his innocence and show them that they are wrong. He could go on a journey to find evidence or seek help from other allies who still believe in him, like Shikamaru or Kakashi.
Jiraiya's reaction might be complex. He might be in awe of Naruto's new power but also sad about his departure. He could see it as a natural progression in Naruto's journey, yet still feel a pang of loneliness. He might start to reflect on his own life and training methods, wondering if he could have done something differently to keep Naruto with him. At the same time, he would be eager to see what Naruto will achieve in the world with his newfound abilities.
Sakura would be devastated. She has deep feelings for both Naruto and Sasuke. She might turn against Sasuke completely and try to take revenge herself. Kakashi would be in shock. He has mentored both and would likely feel like he failed in some way. As for the other ninja from the Hidden Leaf, they would be angry and mournful at the loss of their hero Naruto.
The Naruto fandom would likely be very divided. Some fans would be extremely outraged as it goes against the core values and character of Naruto. They might condemn such a fanfiction.
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.
Naruto might be initially very disappointed. He has always looked up to Jiraiya and expected to be trained by him. So, when faced with the refusal, he could be heartbroken and feel like he has lost a great opportunity.
The other villages might react with a mix of shock and suspicion. They knew Naruto was a powerful force for good in the ninja world. His death could be seen as a sign that something was amiss in Konoha. Some villages might even fear that Konoha was becoming unstable and could pose a threat. Characters like Gaara, who had a special bond with Naruto, would be deeply saddened and might try to find out the real reason behind Naruto's death.