My Dragon System Novel

Sen, the last and most powerful dragon left roaming the skies causing chaos and destruction across the land. When all hope is lost the human race call upon their last hope, a powerful witch. Unable to destroy the dragon the witch uses the last of her power to cast a spell. Sen has not been defeated but has now been reborn as a human.

How will Sen live his life now as a human who he once despised and saw as weak?