One possibility is that the ancient book is cursed. Naruto, being Naruto, doesn't realize it at first. As he starts to read it, strange things begin to happen around him. His friends notice his odd behavior, but Naruto is so intrigued by the knowledge in the book that he continues. Eventually, he has to find a way to break the curse while also using the positive aspects of the knowledge in the book, like some ancient wisdom about friendship and loyalty that helps him strengthen his bonds with his comrades.
In this fanfiction, perhaps the ancient book leads Naruto on a new adventure. It could be that the book has a connection to an ancient clan, and Naruto has to uncover the truth about that clan while also dealing with the power or knowledge the book holds. For example, the book might have a map to a hidden place full of valuable resources or training opportunities. He would then have to figure out how to get there and what to do with what he finds.
Well, he might discover some interesting information about his enemies or other ninjas in the Bingo Book. Maybe he'll be shocked to find out details about certain characters he thought he knew.
In this fanfiction, Naruto might use the magic book to gain new powers. Maybe the book contains spells that can enhance his jutsu.
He might discover some long - lost jutsu. Ancient labs could hold secrets to powerful ninja techniques that have been forgotten over time. Maybe he'll find scrolls with unique chakra - based abilities or old - fashioned weapons with special powers.
Well, Naruto might discover some long - lost jutsu in that ancient library. Maybe there are scrolls that hold the secrets to new and powerful ninja techniques that no one has used in ages.
Well, it could be that Naruto finds a connection to an old shinobi clan in the ancient temple. This discovery could lead him on a new adventure to learn about their history and techniques. There might also be a spirit or an old sage in the temple that imparts some wisdom to Naruto, helping him become a stronger ninja.
Well, Naruto might discover some powerful and long - lost jutsu in the ancient ruins. Maybe it's a super - rare form of ninjutsu that could give him an edge against his enemies.
In this fanfiction, Naruto might discover powerful and ancient jutsu hidden in the tomb. Maybe he'll face some dangerous traps too.
He could face a lot of challenges. People might try to steal the ancient weapon from him. His friends might be worried about the power it holds and try to convince him to get rid of it. But Naruto being Naruto, he would want to keep it to protect the village.
Well, he might discover that the sword has some special powers. Maybe it can cut through any material, or it could have the ability to absorb chakra. He could start training with it to become even stronger in battle.
In the fanfiction, Naruto could meet someone who knows a lot about the Kusanagi. This person could be an old sage or a mysterious traveler. They could teach Naruto how to use the sword properly and unlock its true potential. It could also lead to Naruto getting into some battles where the Kusanagi gives him an edge, and he has to learn to adapt his fighting style to include swordplay.