One idea could be that Naruto is banished to the world of Highschool DxD and his ninja skills make him a unique addition. He might use his shadow clone jutsu to attend multiple classes at once and make friends in a different way than the regular students. Another idea is that his chakra could be mistaken for some kind of special power in the DxD world, leading to both positive and negative attention from different factions.
In a 'Banished Naruto Highschool DxD Fanfiction', Naruto could be banished due to a false accusation in his own world. When he arrives in the Highschool DxD world, he starts to learn about their different power systems. He could end up training some of the DxD characters in his ninja ways, like teaching Issei how to better control his movements using ninja stealth techniques. This would create an interesting dynamic as they combine their powers for various challenges.
One idea could be that Naruto is somehow transported to the world of Highschool DxD. He could use his ninja skills and chakra in the new world, maybe even teach some of the characters there a thing or two about combat. For example, he could show Issei how to better control his power using chakra control techniques.
One idea could be a crossover where Naruto characters are transported to the world of The Highschool of DxD. For example, Naruto himself could end up at the high school and his ninja skills would be quite a shock to the devils and other beings there. He might get involved in the Rating Games, using his shadow clones and other jutsu to his advantage.
A more complex fanfiction could be about a joint mission between the two universes. The leaders of both worlds realize that there is a common threat that only the combined forces of Highschool DxD and Naruto can defeat. So, they send their best characters, like Rias and Sasuke, to work together. This would involve a lot of character development as they learn about each other's cultures and powers.
One idea could be that Naruto characters attend the Highschool DxD academy. For example, Naruto himself could be a new student with his unique ninja skills. He might form an unlikely friendship with Issei. Another idea is a battle tournament where ninja techniques are pitted against the devilish powers in the DxD world.
Well, a plot could revolve around a mystery that involves both worlds. Maybe there is an ancient artifact that has the power to disrupt the balance between the Naruto universe and the Highschool DxD universe. Characters from both sides have to work together to find and protect this artifact. This would lead to a lot of character development as they learn about each other's cultures and values while on this quest.
Perhaps a story where Kuroka transfers to the high school in the Highschool DxD setting and she meets Naruto who is also there for some reason. They could form an unlikely alliance against common enemies. Kuroka's cat - like abilities and Naruto's combat prowess would make for an interesting team - up. And they could also have some comical moments as Naruto tries to understand the strange rules and hierarchies of the Highschool DxD world.
Naruto in a 'Banished Naruto Highschool DxD Fanfiction' can be developed by exploring his reaction to the new culture. The Highschool DxD world has a unique blend of modern and supernatural elements. Naruto, who is used to a more traditional ninja culture, could be both fascinated and confused. He could start to question some of his own beliefs as he sees different ways of life. His relationships with the characters in DxD can also shape his character. For instance, if he falls in love with a character, it could make him more vulnerable and also more determined to protect. His power development could also be linked to his emotional growth, as he discovers new ways to channel his chakra in this strange new world.
A cool plot idea could be a tournament where characters from both Highschool DxD and Naruto participate. The ninjas would show off their jutsu and the devils would display their powers. Also, imagine if Naruto got a Sacred Gear. He could use it to enhance his Rasengan or even create a new jutsu that combines his ninja abilities with the power of the Sacred Gear. Or perhaps, the female characters from Highschool DxD like Rias could teach some of the kunoichi in Naruto about different ways of using their femininity as a power, which could lead to some interesting character development for the kunoichi.
One idea could be a crossover where Naruto characters end up in the Highschool DxD world and have to deal with the devils and angels there. For example, Naruto could use his shadow clone jutsu in a battle against a group of devils, creating chaos. Another plot idea might be that a Leviathan character from Highschool DxD travels to the Naruto world and tries to learn ninjutsu. It could lead to some comical situations as they struggle with chakra control.
A plot could be that the Akatsuki from Naruto are after a powerful artifact in the Highschool DxD world that is related to Lucifer. This would bring the two universes into conflict as the devils and other supernatural beings in Highschool DxD would not want the Akatsuki to get their hands on it. Naruto characters like Sasuke or Kakashi could be pitted against the devils like Issei or Rias. And Lucifer could be in the middle, either trying to stop the Akatsuki for his own reasons or using them to gain more power in his own world.