Yasashii Ryuu no Koroshikata

In this fantasy world, humans and phantoms live side by side. One represents Yang and the other represents Yin.A long time ago, when the world faced apocalypse, the King of the phantoms helped the Queen of the humans and made a promise to his beloved Queen that whenever her descendants faced a similar crisis, his descendants would come and help…Fast-forward to present time. An apocalypse is coming again due to the imbalance of Yin and Yang. A determined phantom King comes to the human world to fulfill his ancestor’s promise. He meets a beautiful Holy Knight by a random twist of fate, and so begins the adventure…