Well, Shikamaru would be one of the characters who would take Naruto's sacrifice very hard. He had always respected Naruto's determination. His reaction might be to become more serious about his duties in the village, feeling that he needs to step up in Naruto's absence. Hinata would be heartbroken too. She had deep feelings for Naruto. She might struggle to come to terms with his loss but also find strength in his selfless act. And all of the Konoha 11 would be united in their grief, vowing to protect the village and each other more fiercely in Naruto's memory.
His friends like Shikamaru would be deeply affected. Shikamaru, who had always respected Naruto's tenacity, would be at a loss. He might think about all the times Naruto pushed forward despite the odds and feel guilty for not being able to prevent his death. Hinata would be inconsolable. She had deep feelings for Naruto, and his sacrifice would shatter her world. The other ninja from different villages that Naruto had befriended during his journey, like Gaara, would also be in mourning. They would see Naruto's sacrifice as a noble act that inspired them to be better protectors of their own villages and to work towards a more unified ninja world.
Hinata would be completely devastated. She has always been deeply in love with Naruto, and his sacrifice would leave her heartbroken. She would still be strong for Boruto, though, and try to support him in any way she could.
The characters' reactions would be complex. For instance, Iruka Sensei, who was like a father figure to Naruto, would be inconsolable. He has watched Naruto grow from a troublemaker to a hero, and this sacrifice would be too much to bear. Shikamaru, being Naruto's friend, would feel a mix of admiration and sadness. Admiration for Naruto's selfless act but sad that he's gone. The kids in the village who looked up to Naruto would be inspired in a way. They would want to be like Naruto and protect the things they love, even if it means sacrificing themselves.
The other characters' reactions would vary greatly. For instance, Gary, who has always had a bit of a rivalry with Ash, would be shocked. He might initially be in denial but then realize the depth of Ash's selflessness. Professor Oak would be extremely sad and would see Ash as a true hero. The Gym Leaders that Ash has faced and befriended would hold commemorative events in their Gyms. They would talk about Ash's courage and how his sacrifice has left a huge mark on the Pokémon world. His sacrifice would also inspire younger trainers to be more like him.
The Weasleys would be devastated. Bill, Fleur's husband, would feel a mix of gratitude towards Harry and intense guilt for not being able to save Fleur himself. Ginny would be heartbroken, having once had feelings for Harry. Hermione would be in shock and would probably spend a lot of time trying to figure out if there was any way they could have prevented it. Ron would be angry at first, angry at the situation and at the bad guys who put Fleur in danger, but also deeply sad for losing his friend.
In such a fanfiction, one possible plot could be that Naruto faces an extremely powerful enemy who is about to kill Kakashi. Naruto, being the selfless hero he is, steps in and uses a powerful jutsu that requires sacrificing his own life to save Kakashi. This could lead to a great deal of mourning among the other characters, especially those close to Naruto like Sasuke and Sakura. They might then vow to carry on Naruto's will and protect the village even more fiercely in his memory.
She would be devastated. Hinata has always loved Naruto deeply. His sacrifice would shatter her world. She might initially go into a state of shock and denial. But eventually, she would become stronger, using her love for Naruto as a driving force to do good in the shinobi world.
Sakura would be devastated. She had known Naruto for a long time and had come to care for him deeply. She might feel guilty for not being able to stop him. Sasuke would also be greatly affected. He and Naruto had a complex relationship. He might regret not being there for Naruto when he made the sacrifice. His friends from the village like Shikamaru and Choji would feel a great sense of loss. They would remember Naruto's always - positive attitude and feel that the village had lost a great light.
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.
The villagers of Konoha would be divided. Some would trust Kakashi and believe there was a good reason for Naruto's death, while others would be furious. The older generation, like Tsunade if she was still around, would demand an investigation. And for Hinata, she would be the most affected. She might feel like she lost her purpose in life with Naruto gone, but then find new strength in seeking justice for him.