Jiraiya could teach Naruto the basic sealing techniques like the Five - Element Seal. This seal can be used to disrupt an opponent's chakra flow. He might also teach him more advanced storage seals, where Naruto could store items or even his own chakra for later use. Another possible technique could be the Summoning Seal, which Naruto could use to summon various creatures or objects.
In the fanfiction, Jiraiya could teach Naruto a variety of Fuinjutsu techniques. He could start with the most common ones like the Scroll Sealing Technique, which is useful for storing things in scrolls. Then, he could move on to more combat - related seals. For example, the Explosive Seal, which can be placed on an object or an area and detonated when needed. Jiraiya could also teach Naruto about the Sealing Chains technique, which can be used to bind opponents. Additionally, he might introduce Naruto to the art of creating multi - layered seals that are more difficult to break.
Well, perhaps the story starts with the fuinjutsu master being sent on a special mission. Along the way, he meets various female characters from different clans. As they see his amazing fuinjutsu abilities, they start to develop feelings for him. The harem aspect then kicks in as he tries to understand his own feelings towards them, all while using his fuinjutsu to solve mysteries and fend off enemies.
Perhaps in this fanfiction, Jiraiya discovers that Naruto is going to be the cause of a major catastrophe in the future. He might have seen a prophecy or some sort of sign that convinces him Naruto has to die to prevent this. It could also be that Jiraiya has been misled by false information about Naruto, which makes him think that Naruto has become an evil force that needs to be eliminated.
One possible reason could be that Naruto feels he has learned all he can from Jiraiya at that point. Maybe he has reached a level in his training where he believes he needs new experiences and challenges that Jiraiya can no longer provide.
One possible reason could be that in this fanfiction, Jiraiya might be preoccupied with other important matters. Maybe he has a secret mission that demands his full attention and he simply doesn't have the time to train Naruto. Another reason could be that there is some sort of conflict or misunderstanding between them that prevents Jiraiya from taking Naruto under his wing. For example, Naruto might have unknowingly offended Jiraiya in some way, or there could be a prophecy or external force that is keeping them apart for the time being.
Jiraiya may provide Naruto with emotional support in fanfiction. Since Naruto grew up without his parents, Jiraiya becomes like a father figure. He encourages Naruto when he's down and helps him understand his own strength. For example, he might share stories of his own past failures and how he overcame them, which gives Naruto the motivation to keep going.
In Naruto fanfiction, the combination of Fuinjutsu and blacksmithing can be really interesting. Fuinjutsu is all about sealing techniques, and when combined with blacksmithing, one can imagine creating weapons with sealed powers. For example, a sword that has a sealing jutsu inscribed on it to trap the opponent's chakra when it strikes. It adds a whole new layer of creativity to the Naruto universe.
In such fanfiction, the blacksmith could be a master of both metal and seals. They might create a chain with Fuinjutsu that can bind an opponent's chakra. This would be a great addition to a ninja's arsenal. They could also work on larger items like gates with Fuinjutsu seals to protect a village or a secret location.
In this fanfiction, perhaps Jiraiya didn't actually die. He was in a hidden place recovering from a serious injury. When he meets Naruto again, Naruto is shocked but overjoyed. Jiraiya then shares his newfound knowledge and powers with Naruto, and they team up to take on a powerful organization that threatens the Hidden Leaf Village. Jiraiya could teach Naruto some advanced Sage Mode techniques that he had been working on during his absence.
The plot might involve Naruto and Jiraiya getting transported to a different dimension. In this strange new world, they have to work together to find a way back home. They meet all kinds of strange creatures and characters. Jiraiya uses his wisdom and experience to navigate through this new environment, while Naruto's determination and growing power help them face the challenges. And during this adventure, Naruto might also develop a new form of his Rasengan, inspired by the things they encounter in this dimension.
One factor could be a new and extremely powerful jutsu. For instance, if Naruto creates a jutsu that combines the power of the Nine - Tails and Sage Mode in a way that Jiraiya can't defend against. Another could be an unexpected advantage like having insider knowledge about Jiraiya's weaknesses. Maybe he learned something from Tsunade that gives him an upper hand.