In 2010, Lee starred in the hit Joseon period/fusion drama "The Slave Hunters", in which she played Un-nyun, who is torn between her past love, a yangban-turned-slave hunter, and her present companion, a general-turned-slave. Lee reunited with her "Green Rose" co-stars Lee Jong-hyuk and Sung Dong-il. Early in the series, some viewers criticized her for having pristine makeup and manicured nails despite portraying a slave on the run, for allegedly wearing a wrist watch onscreen, and her supposedly "inappropriate and gratuitous" cleavage exposure when her hanbok top was removed in an attempted rape scene. Lee opined that those issues weren't a big deal, and had only been magnified by the show's popularity. Her character also received criticism for being an overly passive damsel in distress, and a "Public Menace Un-nyun" (민폐언년) meme circulated, to the extent that writer Chun Sung-il issued a public defense and apology towards Lee.