Baraou no Souretsu EP18 - Your name.

Anne witnesses Richard coming out of Buckingham's room at night. "You know him better than anyone," she says to Catesby. "If he's hiding something, please tell me." To root out Richard's secret, Anne proposes that he dress as a woman and she as a man at a banquet they call "The Devil's Paradise." Despite Anne's intentions, the banquet is a great success, the two of them lost among the admiring crowd. Then Buckingham appears, dressed as the devil.