His friends like Shikamaru would feel a deep sense of loss. Shikamaru, who is usually laid - back, would be angry at himself for not being able to prevent Naruto's death. He might start to work harder to protect the village in Naruto's memory. As for Iruka, he was like a father figure to Naruto. He would be inconsolable and might even retire from teaching, feeling like he failed Naruto in some way.
The other villages would also react. Gaara, who considered Naruto a friend, would be in shock. He might hold a memorial in Suna for Naruto. The Akatsuki members might have mixed reactions. Some might see it as an opportunity to further their own goals, while others who had some respect for Naruto, like Itachi (if he were still alive in this fanfic), might feel a tinge of sadness at the loss of such a powerful and positive force in the ninja world.
Sakura would be devastated. She has known Naruto for a long time and has seen him grow from a loud - mouthed kid to a great ninja. His death would make her question everything. She might become more withdrawn and serious. Hinata would be heartbroken. She had deep feelings for Naruto. She might even lose her will to fight for a while.
The plot of a 'naruto falls to his death fanfic' might involve Naruto sacrificing himself to save others. Let's say there's a powerful attack coming towards his friends. Naruto, being the selfless hero he is, jumps in the way and gets pushed off a high structure in the process. His death would be a great tragedy. His sensei Kakashi would feel like he failed Naruto. And the younger ninjas who looked up to Naruto would be inspired to carry on his legacy, even in his absence.
He would probably be shocked. The fanfic might have some very different takes on combat and characters that he's not used to.
Sasuke would likely be initially suspicious of the Death Korps of Krieg. He's always been cautious around new and potentially powerful forces. However, he would also be intrigued by their military might and might seek to learn from them to further his own power.
Twilight Sparkle would probably be devastated. She looked up to Celestia as a mentor, so she might go into a state of deep mourning at first. But then, she could be motivated to try and fill the void Celestia left, using all the knowledge Celestia had imparted to her.
Sakura would be extremely angry at first. She has known Naruto for a long time and would feel betrayed that he didn't trust her enough to tell the truth. But later, she would understand his reasons and might even help him if she could.
Tsunade would probably be a bit surprised at first. She might be a bit protective of Shizune and would want to make sure Naruto is serious about her. Shikamaru might be the first to notice and just shrug it off as another strange relationship in the village. Sakura might be a bit jealous, not because she has feelings for Naruto in that way anymore, but because she's used to being one of the main girls in Naruto's life. And Kakashi? He'd probably just give Naruto some knowing looks and maybe some advice about relationships if Naruto came to him for help.
The older generation, like Kakashi, would be very cautious. He has seen a lot in his life and would be worried about the implications of Naruto having such god - like powers. He would try to guide Naruto to use these powers responsibly, fearing that Naruto's inexperience with such power could lead to chaos in the ninja world.
Iruka would be inconsolable. He was like a father figure to Naruto in the early days. His death on his birthday would bring back all the memories of Naruto's growth and how far he had come. The village as a whole would go into mourning. Naruto was the hero who saved them multiple times. There would be a sense of hopelessness among the villagers, and they would struggle to find a new source of inspiration without Naruto around.
Naruto would likely be excited yet a bit scared. He'd be eager to make the future a better place but also worried about the bad things he might see. Sasuke would probably be more reserved, analyzing the future information carefully. Hinata would be shy about it but also determined to protect those she loves if she saw any danger in the future for them.
Naruto would react with his usual enthusiasm. He'd see the succubus as someone he could potentially help or befriend. He might not fully understand what a succubus is at first, but his kind nature would lead him to approach her without fear. As for Kakashi, he'd be more guarded. He'd analyze the situation carefully before making any moves, while also keeping an eye on Naruto to make sure he doesn't get into too much trouble.