A possible plot is that Naruto, mute as he is, discovers a new form of magic in the DxD universe that is related to silent communication. This could lead to him becoming a very powerful figure as he can communicate secretly with his allies during battles. Also, his backstory from Naruto could be intertwined with the DxD lore. For instance, his experience with loneliness in his own world could make him more empathetic towards the devils in DxD who are often misunderstood. He could then try to bridge the gap between different factions in the DxD world.
Well, he could be a transfer student in the DxD school. Since he's mute, the other students are initially curious and some might even bully him. But then he shows his amazing combat skills and unique abilities. His muteness could also be a part of a curse or a hidden power. Maybe there's a prophecy in the DxD world that a mute warrior will bring about great change. And Naruto is unknowingly that warrior. As he gets involved with the different characters like Issei and the others, he slowly uncovers the truth about his role in this new world.
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.
One idea could be that the mute prodigy has a unique form of ninjutsu that doesn't require speaking. Maybe they can use sign language to cast powerful jutsus. Another plot could involve the character being misunderstood because of their muteness, but gradually proving their worth. For example, in a mission, they use their silent skills to outwit the enemy.
One idea could be Naruto being mute in a crossover with the Harry Potter universe. He might communicate through magic signs or a special spell - created device. This could lead to him being misunderstood at first, but then his unique abilities, like his ninja skills, would shine through as he helps Hogwarts students in a new way.
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.
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.
One possible plot idea could be a crossover where Naruto characters gain powers from the DxD universe and have to face a new, powerful enemy. For example, Naruto could learn about the Devil Pieces system and use it to strengthen his allies in Konoha. Another idea might be a story where a character from DxD ends up in the Naruto world and has to adapt to its ninja culture while also using their own unique abilities to help or hinder the existing power balance.
One idea could be that Naruto finds himself in the DxD world and tries to use his ninja skills in the battles against devils and fallen angels. Maybe he forms unique alliances with the various factions in the DxD world, like teaming up with Rias Gremory's peerage and teaching them some ninja techniques.
One idea could be a crossover where Naruto's Otsutsuki powers somehow connect with the supernatural elements in DxD. For example, his ability to absorb and use chakra could be related to the magic in DxD. Maybe he could use his Otsutsuki powers to enhance the abilities of the devils or angels he meets in the DxD world.
A plot where the characters have to team up to fight a common enemy that threatens both their worlds. For example, a powerful dark force that can manipulate both chakra and magic. This would force them to learn about each other's abilities and work together.
One idea could be that Naruto discovers a mute girl in a hidden village during one of his travels. Shikamaru gets involved as Naruto tries to find a way to communicate with her. Maybe she has a unique power that only she can use, but because she's mute, she has trouble expressing it. Naruto's determination and Shikamaru's intelligence work together to help her out.