Saya Toma (Erika Toda) is a female detective with an IQ of 201. Takeru Sebumi (Ryo Kase) is a career detective with a distinguished background. They work on cases by postulating the "SPEC" of the unknown criminals and then deduce the criminal's unknown "SPEC" to make arrests. A mystery occurs when bodies are found on a cruiser in the ocean. Saya Toma and Ryo Kase of the Tokyo Metropolitan Police Department are brought in to solve the case.
Space Sheriff Gavan vs Tokusou Sentai Dekaranger features the return of Yuma Ishigaki from 2012’s Space Sheriff Gavan: The Movie and the 2015 Space Sheriff Next Generation films. The first installment will join the two police themed heroes as they face a massive space crime organization.