"Dirty Mama" follows single mother Takako Maruoka, who works as a detective and possesses the highest rate of successful arrests.
Takako Maruoka is on a waiting list to get her daughter into a public daycare center and private daycare centers are extremely expensive. Because of this, Takako takes her baby to work. She has arguments with the baby's father, who does not care about the baby and Takako does not get along with the conservative male detectives. Meanwhile, Takako trains new detective Aoi.