The narrative centers around Nico Hayashi, a clever 14-year-old who expertly manipulates her voice to trick men who are seeking Enjo kōsai. Through her experiences, she gains a deep understanding of human behavior and vocal patterns. When a seasoned criminal boss recognizes her potential, he enlists her to help with various cases. During her initial assignment, she meets Iichiro Sudo, a peculiar computer enthusiast who she affectionately calls "Robo" due to his fascination with toys of that nature. This unlikely duo forms a partnership that leads Nico to assume the moniker "Sexy Voice." Together, they embark on a series of interconnected and character-driven adventures.
