原口元子(武井咲 饰)背负着双亲留下的债务,白天在银行做派遣职员,晚上在银座的俱乐部陪酒。她利工作之便搜集证据,凭借一本写满银行与客户串通用假名户口逃税的证据的黑色皮革手册,勒索1亿8000万日元,变身成为银座俱乐部“卡露内”的妈妈桑。没有任何靠山的她仅凭自己的野心,作为年轻的妈妈桑在黑夜世界里打拼。如“魑魅魍魉”一样的坏人们围绕在她的身边。在各种各样的欲望交织之中,元子孤军奋战。Haraguchi Motoko works as a temp at a bank. To pay off debt that she inherited from her parents, she also works as a hostess at a club in Ginza. Motoko Haraguchi is finally able to repay the debt. At this time, there's chatter that the temp employees will be laid off at the bank. Motoko Haraguchi decides to carry out a scheme she has prepared secretly. She transfers money from accounts opened illegally to her bank account. Altogether, Motoko Haraguchi embezzles 180 million yen. Using her "Kurokawa no Techo" (Black Leather Notebook) which has a list of the illegally opened accounts, she fights against bank branch managers and opens a club in Ginza.