The system might also give the reborn character the ability to transform their body in unique ways. For example, they could use it to create a hybrid form that combines the powers of different races. This new form could be extremely powerful and give them an edge in combat. Along with this, they could use the system to learn ancient magic or techniques that have been lost in the High School DxD world. With these new powers, they could start their own faction or school within the world, changing the power dynamics completely.
The character could develop by constantly using the system to level up their stats. For example, if the system has a feature like a stats page, they could focus on increasing their strength, magic power, and speed. This would make them more capable in battles against the various supernatural beings in the High School DxD world.
In a Naruto and High School DxD fanfiction, there could be a scenario where the protagonists of both stories meet in a neutral dimension. Issei from High School DxD might be intrigued by Naruto's ninja skills and determination. Naruto, in turn, could be curious about Issei's Sacred Gear. They could start training together, sharing their knowledge and skills, and ultimately have to face a common enemy that threatens both their worlds.
There could be a really interesting fanfiction where the Queen of Blades from StarCraft gets inserted into the High School DxD universe. Maybe she could be a powerful new character in the school, causing all sorts of chaos or perhaps she teams up with the main characters to fight against a common enemy. It all depends on the creativity of the writer.
In a Naruto - High School DxD fanfiction, the power levels would be really interesting to explore. Naruto's sage mode and tailed - beast forms are extremely powerful. In the DxD world, there are different power systems like the Sacred Gears. It would be fascinating to see how Naruto's powers interact with the powers of the DxD characters. For example, could his Rasengan be enhanced by a Sacred Gear? Or how would he fare against a devil's magic?
The story mainly follows Issei Hyodo, a high school student who gets killed on his first date and is later resurrected as a devil. He then becomes part of the Occult Research Club at his school. There, he gets involved in various battles against other supernatural beings, all while trying to become stronger and also dealing with his new devilish desires and relationships with his female comrades.
One possible scenario could be that Naruto characters are somehow transported to the world of High School DxD. Naruto's ninjutsu skills would be quite a shock to the devils and angels in that world. For example, Sasuke's Sharingan could give him an edge in battles against the supernatural beings in High School DxD. And Naruto's never - give - up attitude might inspire some of the characters there to face their challenges more bravely.