The True Demon Lord

A Hero who sacrificed himself to save his world managed to be transported into a strange realm and met a goddess.

He was given the chance to be brought to a new life in another world.

A chance to become a hero once again said the goddess

The goddess shocked, in what the hero responded.

"Ehh... I want to become the demon lord though."

They both argue for awhile, ultimately the hero won and his wish was granted but there was a catch.

He will still have the tremendous power of the demon lord but he has to built his empire from scratch.