To crack down on the rise in waterborne crimes, the Metropolitan Police Department establishes the “Tokyo Water Police Department (Suijo Division).” However, those gathered there are a disparate group with different backgrounds and values. Their leader, Ikari Takuma, has worked for over 20 years as a local detective; Kusakabe Shun, an ambitious officer transferred from headquarters; and Arima Reiko, a maritime technician in charge of piloting boats—these and other colorful members form the Suijo Division. Together, they take on crimes occurring in Tokyo’s seas and rivers, gradually forging unity as a team through solving cases.