Unholy Blood is a webtoon about Hayan Park, a seemingly ordinary college student who hides a dangerous secret: she is the last pure-blooded vampire, known as a "Holy Blood." After her parents were murdered by a rogue vampire organization called the Union, Hayan has been living in hiding, suppressing her powers. When she accidentally kills a thug with supernatural abilities, she attracts the attention of Euntae Hwang, a detective from a secret task force hunting the Union. Forced to reveal her true nature, Hayan teams up with Euntae to take revenge on the Union, unleashing her full, fearsome vampire strength. Readers enjoy the series for its intense, fast-paced action, a powerful and badass female lead who dominates her fights, a slow-burn romance between a vampire and a human detective, and the satisfying blend of dark fantasy, revenge, and modern supernatural warfare.