Well, the plot could involve Naruto exploring new ways to use the Katon Gouka Mekkyaku. Maybe he's in a battle against a powerful enemy who has some sort of resistance to fire techniques. So, Naruto has to combine it with other jutsus or find a new way to channel the chakra for this technique to make it more effective. He could also be teaching the technique to some of the younger ninjas in Konoha, which would lead to some interesting training scenes and character development for those new ninjas.
The plot might center around the origin of the Katon Gouka Mekkyaku. In the fanfic, it could be revealed that this technique was once used by an ancient and powerful ninja clan. Naruto discovers some hidden secrets about this clan while trying to master the technique better. This could lead him on a journey to find ancient scrolls or talk to old sages who might know more about it. Along the way, he would face various challenges and also learn more about the history of his own village and the ninja world in general.
One possible plot could be that Naruto accidentally unleashes a much more powerful version of the Katon Gouka Mekkyaku during a training session. This causes a lot of chaos in Konoha. As a result, he has to figure out how to control this new power. He might seek help from his friends like Sasuke or Sakura. They could try different methods, like using medical ninjutsu to balance his chakra or Sasuke's sharingan to analyze the technique better. Meanwhile, there could be some villains who are interested in this new power of Naruto's and try to steal it for their own evil purposes.
Chapter 354, "Mr. Luo, Aren't We Unfamiliar?", is the clearest early answer because it turns Miss Jin Zhen's situation into a concrete plot event. The chapter gives readers a real answer by opening on Lin Manru simply couldn't believe what she had heard.
Chapter 366, "The Safety Lock Got Flattened?!", is the clearest early answer because it turns Xiao Wu's situation into a concrete plot event. A useful checkpoint is the way the scene starts with You're finally out!" Xiao Wu saw Jiang Li and the others from a...
Chapter 350, "The Male Lead Actually Came Out to Clear Jiang Li's Name?!", is the clearest early answer because it turns Xiao Ling's situation into a concrete plot event. Early on, The criticism on Weibo continued to ferment..
Chapter 196, "I am the one with the most potential!", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. The chapter gives readers a real answer by opening on Wen Jiaojiao was on the verge of a breakdown.
Chapter 247, "Madam, Your 2000 Kilograms of Sweet Potatoes, Please Check and Accept", is the clearest early answer because it turns Shu Yan's situation into a concrete plot event. It opens with Facts have proved that arch-enemies often understand each other the...
Chapter 365, "Are You Sick?", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Jiang Li didn't make a sound, she merely glanced in the direction of...
Chapter 544, "I Shouldn't Have Stopped You from Pursuing Shang Shaojing Back Then", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event.
Chapter 397, "Talent Show Program", is the clearest early answer because it turns Zhou Wenshu's situation into a concrete plot event. The chapter gives readers a real answer by opening on Second Aunt, I know you're worried about Shixu interacting with...
Chapter 343, "He Can Support Jiang Li for a Lifetime", is the clearest early answer because it turns Lifetime Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from But she suddenly acted mischievously indifferent, "Are you a...
Chapter 396, "The Shang Family Now Follows My Orders", is the clearest early answer because it turns Shang Shaojing's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Doomsday Beehive" featured a male supporting character who was...