Summoned to Another World as a Hero!?

Suddenly transported to another world, I'm told that because I'm a hero, I must save the nation if I want to return to my original world. Common sense doesn't apply here, life is cheap, there's no ethics or morality, and on top of that, sexual morals are loose. Will I be able to keep my sanity in this world? However, I do have power. As a sense of mission gradually awakens in me, I create a harem to save the empire??