Here, we propose a counterintuitive use of a hybrid system where the coherence time of a quantum system can be significantly improved by coupling it with a system of a shorter coherence time. Coupling a superconducting flux qubit with a single nitrogen-vacancy (NV) center, a dark state of the NV center naturally forms after the hybridization. We show that this dark state becomes robust against noise due to the coupling even when the coherence time of the flux qubit is much shorter than that of the NV$^-$ center. Our proposal opens a new
way to use a quantum hybrid system for the realization of quantum computation, quantum repeater, and quantum metrology.