Unseong observed his mentor's violent death in a universe conquered by accomplished fighters. The execution of his mentor, accused of using prohibited demon techniques, was unfair and left Unseong without any power to react. Although he attempted to seek revenge, Unseong was unable to overcome the perpetrators and eventually met his own death. Fate, however, intervened, returning him as an adolescent prepared to train in an elite unit under the leadership of a demon-led organization. To accomplish his revenge, he must embrace the darkness within him and use its power to reach his ultimate goal.