I'm not sure which one is the most popular specifically, but there might be some on platforms like FanFiction.net or Archive of Our Own. You can search for 'naruto godlike katon' and look at the ones with high ratings and a lot of reviews.
There are fanfictions where the 'naruto godlike katon' aspect is combined with some sort of hidden family heritage related to the fire element. In these stories, the character not only has a powerful katon ability but also discovers a deeper connection to their family's past and the secrets of the katon jutsu that have been passed down. This often leads to them becoming even more powerful and respected in the Naruto universe.
It could be Naruto himself who discovers and uses the Katon Hijingakure no Jutsu in the fanfiction. Since he's always exploring new jutsus and pushing his limits.
Well, in this fanfiction, the Katon Hijingakure no Jutsu might have unique characteristics such as a more intense and hotter flame compared to the regular Katon techniques. Maybe it also has some special shape or movement pattern that is distinct from other fire - based jutsus in the Naruto universe.
Sasuke could be a major rival. Since Sasuke also has strong fire - based abilities, he might see Naruto's growth as a Katon master as a challenge to his own skills. Another potential rival could be a new character introduced in the fanfiction, a prodigy from another village who is also focused on mastering Katon. There could also be older, more experienced ninja within the Leaf Village who might initially doubt Naruto's ability to be a true Katon master and thus become rivals in a sense as they test his skills.
One plot idea could be Naruto's journey to master the Katon techniques. He might start with basic Katon jutsus and struggle to control the fire at first. For example, accidentally setting things on fire in the village while training. Another idea is that he discovers a new, powerful Katon technique that was lost in history and has to face off against enemies who also want to obtain it. Maybe he teams up with Sasuke, who has his own fire - related abilities, and they combine their powers in an epic battle.
It could be used as a form of communication. For example, Naruto could use different intensities and patterns of the Katon Gouka Mekkyaku to send messages across long distances. This would be a very unique application compared to its normal use as an offensive technique.
A plot could revolve around Naruto teaching the Katon Gouka Mekkyaku to a new generation of ninja. This could show his growth as a teacher and how he adapts the technique for different learning styles among the young ninja. He might also have to face some challenges when some of the students misuse the technique at first.
Yes, there are likely fanfictions with such a concept. Fanfiction writers often come up with unique and creative ideas, like a godlike Naruto who is blind. It could explore how Naruto overcomes his blindness while still having his godlike powers, perhaps delving into his other senses and how they are heightened to compensate. There might be different interpretations of how his relationships change as well, such as with his friends and foes.
One great 'Katon Naruto fanfic' could be 'The Blazing Trials of Naruto'. In this fic, Naruto discovers a new form of Katon jutsu through intense training. It's really exciting as it shows his growth not just in power but also in character.