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.

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.