Hunting or being hunted is the basic law of the food chain, used to refer to the relationship between hunter and prey. Evil and humans are enemies that cannot save heaven, so the fate of demons captured in human hands is very tragic. Kiera is a devil who lives under the human condition. Since childhood, people chased and killed him, and he had to flee into dangerous deep forests. Kiera is perhaps the person who best understands the laws of predation. She realized that if she didn't want to become prey for others, she had to turn herself into a top hunter. While living a peaceful life with his assassin training base teammates, Kiera encounters a dangerous hunter. The one who put the people around her in danger. Once again targeted as prey, she realized that she was not as strong as she thought. Leaving his identity behind, Kiera set out for the town, where the intelligence organization's headquarters headed the operation. To find the mastermind behind him, Kiera joins the intelligence organization, becoming a half-time assassin. As soon as the curtain gradually opened, her background was clarified. Standing in front of a chessboard long calculated by the enemy, can Kiera win? Become someone else's prey or transform yourself into a predator? It's you, which path will you take?