There are two kinds of people with special abilities: villains, who are driven by their evil desires, and psykers, who pursue justice and work against villains. Cassian Lee is a very powerful psyker with a good heart. But one day, when he visits his friend in Greece, things take a wrong turn. Following an unexpected chain of events, Cassian ends up in the body of a Korean high school boy... who has just become a villain! Will his sense of justice win in the end or will he end up becoming a cold-blooded villain? (Source: Webtoon Entertainment)