Hoshino Mitsuko is a determined and hard-working woman living in the 1930s, where career women are a rarity and looked down upon. Despite rampant sexism and pressure to "stay home," she's determined to prove herself as a successful detective no matter what. One day, she's approached by the handsome waiter Yoshida Saku, who presents Mitsuko with her very first solo case. Together, the two work closely to solve the mystery, and Mitsuko finds Saku quite capable--but very curious--and takes him on as her new assistant. Can this duo tackle cases and the turbulent atmosphere of the Showa era?