She saved him when he was at his lowest, now he'll do anything for his mistress. Anything. (Slight femdom and spoilers)

There was nothing left for him in his old world, so why not move to a new one and see where life would take him?

Immortality. Many seek out a way to live forever, whether they want power, more time to finish their magnum opus, or just out of a fear of death. They would easily turn themselves into monsters or sell their souls for a chance at it. However, there is one boy who has sought a way to live forever out of the love he has for those closest to him.

What does a god do when he's bored out of mind? Go to the human world and have an adventure of course!