It is convenient the hero party had exactly the amount of resources to finish the demon king. Why did he think it was the demon king anyway? I expected the real demon king walking out from behind the table and laugh at the hero, “you spent all your energy defeating my deputy, now die” but fortunately for him it didn’t happen.

So, now the hero restarted and have a chance to redo the adventure and minimize the amount of losses with his foreknowledge. Let’s see if this anime can make it interesting.