Shouldn't the little girl magician be able to spot the seals Aria used to cripple Akira? Those seals are basically the only thing preventing Akira from being one of the most powerful individuals in the world, so curing his mana ailment is the same as removing those seals. Things will get interesting if Prol tells Akira all about those artificial seals, whether she can remove them or not. Assuming Akira isn't a blistering idiot (which he very well might be, considering that whole debt fiasco), he would immediately understand Aria sealed his mana. Even if he is happy to be a powerless nobody, it still means Aria would have lied to him about such an important thing.