The Elected Demon

For the sake of peace, some people from the human race and the demon race conspired to select a demon with the power of the bloodline of the demon emperor. They planned to slowly train him and send him to the tomb of the demon emperor to find a way to make peace between humans and demons. But the person chosen is a bit useless! It's a bit hard to hold on to the wall. Cloning technology is growing rapidly, reactionary forces are constantly obstructing it, and hopes are constantly being dashed. Just trying hard will not bring a good result.