I don't know for sure as it's a fanfiction. It could be Naruto himself using the mega buster. Or it could be a new character created specifically for this story.
Well, in fanfiction, it could be that Sasuke is the main character who gets involved with the mega buster. He might be on a quest to either obtain it or destroy it because it poses a threat to his goals. Another possibility is that a completely original character is the main focus. This character could be an outcast ninja who discovers the mega buster and uses it to try and find their place in the Naruto world. They might face opposition from the established ninja villages who are either afraid of the power or want it for themselves.
Since it's a fan - made story, the main characters could be a group of young ninjas who stumble upon the mega buster. They then have to figure out what it is and how to use it without getting into too much trouble. It could also be that an older, more experienced ninja is the main character and they see the mega buster as a way to pass on their knowledge and skills to the next generation. There are so many possibilities when it comes to fanfiction characters.
Chapter 273, ", Sun Lord (6k additional)", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. It opens with Now, Gu Hang has exposed a scandal about Blackbird Heavy Industries... and closes on This was a legal rationale that could stand up..
Chapter 281, ", Torn to Pieces", is the clearest early answer because it turns Wind Falcon's situation into a concrete plot event. The chapter gives readers a real answer by opening on Irong Fetches would never be caught 'off guard'. and ending on The situation had to be resolved quickly and could not be delayed any.... In story terms, the chapter closes with He didn't know how to respond., which gives Wind Falcon a stronger narrative position and pushes the power growth onward.
Chapter 305, ", Let's see the situation", is the clearest early answer because it turns Rage Bear Legion's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Lucy Lee Ko Xi was one of the few whose military rank did not... and follows through with This not only prevented the enemy formation from 'healing' their....
Chapter 284, ", Not So Loyal Advice", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. It opens with Now, Gu Hang really started to feel a headache. and closes on Perhaps during an expedition, they might lose track of where they are....
Chapter 299, ", Truly Tough Fate", is the clearest early answer because it turns Truly Tough Fate's situation into a concrete plot event. It opens with Gu Hang wasn't at all embarrassed, "If you want to talk, I'll keep... and closes on Reporting upwards that they had produced an A-level spiritual energy.... The key payoff is that the chapter closes with Gu Hang was nothing if not accommodating: "Okay, Master Wang, we can talk later.
Chapter 351, ", 'Prey'", is the clearest early answer because it turns Army Groups's situation into a concrete plot event. A useful checkpoint is the way the scene starts with He paused, then continued, "Next, I will assemble a division to... and follows through with Thus, Fino City steadily pressed forward a distance of twelve....
Chapter 289, ", The Great Victory of Operation Flash Tail", is the clearest early answer because it turns Operation Flash's situation into a concrete plot event. The setup is Hence, Lion Tanks, Strider Combat Vehicles, and 155 Towed Artillery..., but the pressure keeps building through They had to vent their shame in this manner..
Chapter 238, ", 'Unique' upgrade sequence unlocked", is the clearest early answer because Rage Owl Star finally turns buildup into a real advancement. The setup is To remain human, or to ascend to godhood?, but the pressure keeps building through This choice now lay before Gu Hang..
Chapter 442, "a major turning point", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. It opens with Relying on the many industries generated by road transportation, such... and closes on And Gu Hang didn't bother to find new explanations—he couldn't find.... The key payoff is that the chapter closes with 4.2k, which gives family politics a stronger narrative position and pushes the power growth onward.
Chapter 287, ", Let the Grenade Launcher Roar!", is the clearest early answer because it turns Valen Zu's situation into a concrete plot event. Early on, But just as they were diligently digging holes, something happened.. By the end, The former would have to face a military court, or on the frontline,.... Inside the broader faction conflict storyline, the chapter closes with There was no need to wait for the enemy to come closer before firing. This was not an ambush;