The author really has to rub it in by making Akira even thank Aria in his mind, even though she cursed him. If not for the fact the dude actually wants to live as a weakling mob character, it would be even more jarring. But does he actually? He racked up a debt of 10,000 gold without a second thought, as if he was some big mofo, for whom such an amount is mere pocket money. Yet it's not, and only the anguish the debt generated made him accept this mission.
I'm not sure if I want Aria to be sorry for what she had to do or not. She definitely would be a better person if she was, but she might be a more interesting character if it was just her duty and she doesn't really care. Although I suppose the latter would make her an enemy in the future.
All that aside, I really hope the MC's mana constitution will be fixed soon. It would be highly annoying if he was a powerful character, but only when there's someone else right next to him, pumping mana into him. Without the support, he would be nothing. If it was a world where everyone was like that, it would be okay, but if only the main character of an action manga is like that, it's just wrong.