In this kind of fanfiction, his sister would probably be devastated. She might go through a long period of grief and could potentially vow to avenge Naruto's death if it was caused by someone.
In the Naruto series, Naruto doesn't have a biological sister in the original story. So in this fanfiction, the author probably creates a new character to be his sister. It could be an original character with unique abilities and a complex backstory that leads to the situation where Naruto dies by her hand.
Sasuke would be deeply affected. He and Naruto had a complex relationship, from being rivals to friends. He would likely feel a sense of guilt, as if he should have been there to protect Naruto. Sakura would be heartbroken. She had always cared for Naruto, and seeing him die in such a tragic way in front of his parents would make her feel helpless. His parents, on the other hand, would be in utter despair. His father might feel like he failed as a father again, not being able to protect his son this time either.
In such a fanfiction, Naruto could die in various ways. Maybe his sister is somehow possessed and attacks him fatally. Or there could be a situation where she accidentally causes his death during a fight due to a lack of control over her power.
Perhaps Naruto is poisoned by a powerful new villain. His parents are revived just in time to see him succumb to the poison. This event could trigger a series of events where his friends and the entire village vow to avenge his death. His parents might then decide to stay in the living world to help in this quest for vengeance, despite the rules of the afterlife.
In this fanfiction, it could be that Naruto's sister is being targeted because she has information that could expose a powerful and corrupt group. Naruto, being the selfless hero he is, shields her from their attacks. His death becomes a symbol of resistance against this group, and his sister then takes on the task of bringing them to justice.
One possible storyline could be that Naruto's sister is being targeted by a powerful and vengeful enemy. Naruto, being the selfless hero he is, throws himself in front of a deadly attack meant for her. His death could then inspire his sister to take up his ideals and become a great ninja in her own right. Another idea is that there is a dangerous mission to protect a secret related to their family that only his sister can safeguard in the future. Naruto sacrifices himself to ensure she can complete this important task. And perhaps in his last moments, he passes on his most powerful jutsu or some important knowledge to his sister to help her in her future battles.
One consequence could be Hinata's complete emotional breakdown. She has always been in love with Naruto. His death would shatter her world. She might become withdrawn and lose her will to fight. In the Naruto universe, she is a strong - willed kunoichi, but this event could change her entirely. She could also vow revenge if Naruto's death was due to an enemy, and this could lead her on a dark and dangerous path of seeking vengeance.
His death would be a huge shock to the ninja world. Naruto is a well - known and respected figure. His sacrifice for his sister would be seen as an ultimate act of heroism. It could inspire a new generation of ninjas to be more selfless and protective of their loved ones. Also, the villages that Naruto had strong relationships with, like Konoha, would likely hold memorials for him and his story would be passed down as a cautionary and inspiring tale.