Having godly powers is not as good as it sounds

An Intelligent Highschool kid visits Kyoto after winning a quiz competition on behalf of his school. He gets lost while exploring some relics and decides to spend the night sleeping under a shrine. When he wakes up he finds himself with a kid calling himself kami. kami tells the kid that he's dead and that he is going to be his ally in defeating demon lord from now on. He receives godly powers for this purpose, but for him having godly powers aren't as good as it sounds.