Highschool DxD: Perfection System!

"Ah, darn it. I really don't understand anything," whispered a 14-year-old boy as he looked at his notebook. He was about to enter his vacation period, and he had some pending homework. Being the expert procrastinator he was, he chose the easy path. He left everything until the last moment! However, everything changes for him at the most opportune moment. Something that seems like a simple system to help him study at first, becomes the foundation of his new life! - The system is the foundation of this story, so it will be a recurring and essential element in the story as much or even more than the protagonist. If you don't agree with that, then it's better not to read this fanfic. - Mc is a Gary Stu