A really interesting plot could revolve around the Second Hokage's relationships. For example, his relationship with the other clans in the village. He might have to deal with the Uchiha clan's growing unrest. This could lead to him making difficult decisions to maintain the peace in the village. He could also have a mentor - mentee relationship with a young and talented ninja, guiding them to become a great shinobi.
Well, a plot could be set during a time when the Second Hokage is trying to improve the village's defenses. He decides to create new jutsu or ninja tools. Along the way, he discovers a long - lost secret about the founding of the village. This discovery puts him in a difficult position as it could either strengthen the village or cause internal strife if the wrong people find out. He has to navigate through this while also dealing with external threats to the village.
One plot idea could be Naruto discovers a long - lost jutsu created by the Second Hokage. He then has to master it to defeat a new, powerful enemy threatening the village. Another could be that Naruto travels back in time and meets the Second Hokage, learning valuable lessons about leadership and sacrifice from him. Maybe the Second Hokage's spirit appears to Naruto in a time of crisis and imparts some secret knowledge only he knew.
A really interesting plot could be Naruto traveling back in time to the era before he was born. He could meet his parents and other important figures in the village's history. This would give him a chance to understand the roots of the village better and also learn some new jutsu or strategies that he could bring back to his own time to make the Hidden Leaf even stronger as a Hokage.
Another plot could involve Naruto and Hinata dealing with a new threat to the village that specifically targets their family. They must protect their children and the village while also maintaining their relationship. This could include Hinata using her Byakugan in new and creative ways to help Naruto in his leadership role.
One idea could be focusing on how the Sixth Hokage deals with new threats from outside the village. For example, a long - lost clan with a powerful and dangerous jutsu resurfaces. The Sixth Hokage has to use both diplomacy and strength to handle the situation.
One idea could be exploring the Godaime Hokage's early days in the role. Maybe she has to deal with a new and unexpected threat to the village that tests her leadership in ways she hadn't anticipated. Another could be a story where she has to make a difficult decision regarding the future of a young ninja with a troubled past, balancing the village's safety and the ninja's potential.
One idea could be Naruto facing a new and powerful enemy that challenges the very foundation of the Hidden Leaf Village. This enemy might be a rogue ninja with a grudge against Naruto for becoming the Sixth Hokage. Another plot could involve Naruto trying to implement new policies in the village but facing opposition from the traditionalist shinobi. For example, he might want to change the way chunin exams are conducted to be more inclusive, but the old - school ninja don't like the changes. Also, a plot could revolve around Naruto having to deal with a mysterious disease that is affecting the ninja in the village and he has to find a cure while still maintaining his duties as Hokage.
One idea could be exploring how the Sixth Hokage deals with the remaining threats from the Akatsuki. Maybe some members who were thought to be dead actually survived and are plotting revenge. Another could be focusing on the internal politics of the village. As the Sixth Hokage, there would be a lot of pressure to make decisions that satisfy different clans and factions within Konoha. Also, the Hokage could be involved in training a new generation of ninja with unique abilities, passing on the wisdom and skills Naruto has taught him.
One idea could be a fanfic where the 7th Hokage, Naruto, has to face a new and powerful enemy from a hidden land that was previously unknown. This enemy has a unique jutsu that can nullify Naruto's chakra. Another idea is a story about Naruto's daily life as Hokage, dealing with the paperwork while also trying to find time for his family.
One plot idea could be exploring the 5th Hokage's early days in the role. Maybe she had to deal with internal political unrest in the village. Another could be her training a new generation of shinobi with a unique teaching style. Or perhaps a story where she has to face a long - lost enemy from her past that resurfaces to challenge her leadership.
An interesting plot for Naruto's Sandaime fanfiction might be to create a story where the Sandaime discovers a hidden power within Konoha that could either save or destroy the village. He has to make difficult decisions on how to handle this power. Maybe it's a powerful jutsu that was sealed away long ago. Additionally, you could explore his role in the creation or discovery of some of Konoha's most important landmarks or institutions. He was in charge for a long time, so he surely had a hand in many things. Or, you could write about a time when he had to make a great sacrifice for the sake of the village, like giving up his own chakra to protect a powerful seal.