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 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.
Another option is Reddit. There are Naruto - related subreddits like r/NarutoFanfiction. You can post a request asking for 'Katon Naruto fanfic' and the community might be able to point you to some great reads or even share their own creations.
Asuma's training might make Naruto more disciplined. Naruto is known for his impulsive nature, but under Asuma's guidance, he could learn to think before acting.
In a Naruto saves Asuma fanfiction, Naruto could use his new jutsu skills. Maybe he discovers a way to reverse the damage done to Asuma. It could be related to his Sage Mode powers, which he could use to heal Asuma's wounds.
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.
One popular 'asuma and ino fanfic' could be 'Asuma's Legacy and Ino's Growth'. In this fanfic, it might explore how Ino is influenced by Asuma's teachings and how she incorporates his wisdom into her own ninja development. It could show her evolving as a character, becoming stronger not just in terms of combat skills but also in her mental fortitude.
One common theme is mentorship. Asuma, being an experienced ninja, can be a mentor to Ino. So, many fanfics explore how Ino learns from Asuma, like in terms of combat techniques or ninja ethics.