Peerless Agent: The General's Second Daughter

A leader of the Five Kage in the 21st century dies taking a bullet for a brother and transmigrates to another world, reborn in the Great Night. She is a direct descendant of the Phoenix clan. Everyone who ever wronged her will pay, not a single person will be spared.

He is the Great Night's eldest prince, a god of war who dominates the battlefield and is like a demon in the eyes of the people. Cold and overbearing toward everyone else, he wants nothing to do with women. Only with her is he gentle and commanding, giving her everything that's best. Even the slightest furrow of her brow breaks his heart!