Reiko Houshou, heiress to a large conglomerate, seems like any other wealthy lady. However, not many people know that she is a rookie detective for the Kunitachi Police Department. In addition, she hides her identity from her incompetent boss, Kyouichirou Kazamatsuri, a flashy heir to his family's motor business.

During an investigation involving her college friends, Reiko has trouble identifying the culprit and their motive. Out of nowhere, a man approaches Reiko and introduces himself as Kageyama, her newly assigned butler. As soon as Reiko confides in him about her worries, he criticizes her lack of deduction skills and helps her quickly crack the case. Now with the sharp-tongued Kageyama at her side, Reiko may just become the detective she desires to be.