Na Joo-ri and Ahn Joo-ri have been friends since high school. Two people with the same name but opposite personality, Jal-joo, a married women who enjoys free sex, and Ahn Joo-ri, who keeps her virginity before marriage. Yong-jin, who promised to marry Ahn Joo-ri, has yet to have sex. The frustrated Yongjin tries the first night with Ahn Joo-ri with the help of Na Joo-ri.