One idea could be to have Naruto end up in the DxD world through a strange portal. He might bring his unique ninja skills and chakra system, which would be a huge shock to the devils and other beings in the DxD world. Maybe he teams up with Issei to fight against a common enemy that threatens both the ninja world and the DxD world.
Well, perhaps a fanfic could revolve around a Shinju - influenced character from Naruto coming to the DxD world and starting a school for both ninjas and devils/angels/fallen angels. They teach the DxD characters about chakra and how to use it in combination with their existing powers. In return, the DxD characters teach the Naruto - style character about the different social and power hierarchies in their world. This would lead to a lot of interesting interactions and potential for both comical and serious storylines.
Perhaps Naruto has a unique power that is related to both worlds. He could form a team with some of the DxD characters like Issei. They could go on adventures together, fighting against common enemies. His rasengan might be enhanced by the magic in the DxD world.
One idea could be a crossover where Naruto's skills in combat and his never - give - up attitude influence the events in the Highschool DxD world. For example, he could help Issei train in a new and unique way, combining ninja techniques with the Boosted Gear. Another plot could involve Kuroka getting involved in a conflict that requires Naruto's special abilities to solve, like a mystery related to ancient ninja scrolls that have somehow ended up in the DxD universe.
One idea could be that Naruto characters attend the Highschool DxD school. Naruto could use his shadow clone jutsu to cause all kinds of chaos during classes or P.E. Another is that some of the Highschool DxD devils could be interested in Naruto's chakra and try to make a deal with him. Also, the ninjas from Naruto could introduce their unique fighting styles to the students at Highschool DxD, leading to some epic battles in the schoolyard.
A possible plot is that Naruto's godlike chakra is mistaken for some kind of extremely powerful sacred gear. This leads to various factions in the Highschool DxD world trying to either recruit him or steal his power. He could also form unique bonds with the characters, for example, helping Issei with his training in a way that combines ninjutsu and his own techniques.
Well, a plot could involve Naruto learning about the Devil Pieces in the DxD world and trying to figure out a way to use his chakra in a similar way to reincarnate or empower allies. Or maybe some of the DxD characters end up in the Naruto world and have to adapt to the different power systems there, like learning how to use ninjutsu.
Another plot could involve a fusion of Naruto's ninjutsu and the sacred gears in Highschool DxD. For instance, Naruto could teach some of the characters in DxD how to use chakra, and in return, they could show him how to better utilize the powers of the sacred gears. This exchange of knowledge and power could lead to the development of new and exciting abilities for all the characters involved.
One plot idea could be that Naruto, with his ninja skills, gets transferred to the High School DxD world. He might accidentally join the Occult Research Club and use his Rasengan to defend the club from various threats. His positive attitude and never - give - up spirit could inspire the DxD characters and also attract the girls in the harem, leading to some comical and action - packed situations.
An OC who is a human detective investigating strange occurrences in the 'Highschool DxD' world. They could end up forming an unlikely alliance with the devils. This would bring a new perspective as they try to understand the complex relationships and power dynamics in the series.
One idea could be that Naruto and Sasuke are transported to the DxD world and they have to learn the new rules and powers there. They might team up with some of the DxD characters to face a common enemy.