Electromagnetically induced transparency (EIT) is a signature of quantum interference in an atomic three-level system. By driving the dressed cavity-qubit states of a two-dimensional circuit QED system, we generate a set of polariton states in the nesting regime. The lowest three energy levels are utilized to form the $Lambda$-type system. EIT is observed and verified by Akaikes information criterion based testing. Negative group velocities up to $-0.52pm0.09$ km/s are obtained based on the dispersion relation in the EIT transmission spectrum.