No matter how hard he tries, Tinto's level never increases, and he's been dubbed the "enemy of God." After he gets kicked out of the party he's been in, the goddess Estelle appears before him, kneeling and apologizing. It turns out that it was because of her mistake that Tinto was still at level 0! By way of apology, he's given 100 times the experience points he would have gained up until that point, and overnight, Tinto becomes the strongest adventurer! (Source: Hifumi Shobo, translated)