Kamizuru Ryoko, a brilliant female detective who is a master in disguises, teams up with Takayama Nobuhiko, a young man who has an IQ of 140 but is uncomfortable in the presence of women. She fulfils all manner of requests except for murder and assault cases, but her request fee is a high price at 2 million yen.
Kiyama joins the agency after a chance encounter, and though he appears perfect at first glance, he has an extreme area of weakness when talking to women. He is drawn in by the absurdly unpredictable methods of the Detective Agency and utilizes his brilliant mind to support Kamizuru, who is willing to use any means at her disposal, and the combination of the two leads them to solve cases in the most lively way.
Adapted from the novel "Goritekini Arienai: Tantei Kamizuru Ryoko no Kaimei" (合理的にあり得ない ～探偵・上水流涼子の解明～) by Yuzuki Yuko (柚月裕子).