Yuno would be completely shattered. He has always seen Asta as his rival and friend. He would probably blame himself for not being strong enough to protect Asta. His grief might turn into a cold determination to change the world in Asta's memory. Noelle would be heartbroken. She has deep feelings for Asta, and his death would be a huge blow. She might become more withdrawn initially, but then find strength in wanting to carry on Asta's ideals.
The older characters such as Kakashi would be cautious. They would recognize Naruto but also be worried about the implications of someone from the future being in the present. They would want to know if his presence could change the future in a negative way. For example, they might fear that his actions could lead to the earlier awakening of a powerful enemy. As for the villains, they might see future Naruto as a threat and try to eliminate him as soon as possible. Orochimaru, for instance, would be very interested in Naruto's future powers and might try to capture him to study. And the new generation of ninja in the past would look up to future Naruto, seeing him as a symbol of what they could become.
I'm not entirely sure if it's a popular genre. Fanfiction can cover a vast range of themes, and while there may be some works with such themes, it might not be mainstream. The Black Clover fanfiction community has a lot of different types of stories, from adventure and friendship to power - up scenarios.
Black Clover tells the tale of Asta's journey to become the greatest mage. It's full of magic, friendships, and intense battles. Asta's perseverance and the complex web of relationships make it an engaging story.
Yes. The Black Clover light novel offers additional insights and background details that aren't present in the main series. It's a treat for fans who want to delve deeper into the world.