Core-collapse supernova is the explosive death of a massive star and is thought to be re-energized by neutrino heating. Because neutrino transport requires accurate treatment, we have developed and run the Boltzmann-radiation-hydrodynamics code, which solves the Boltzmann equation for neutrino transport, hydrodynamics equations, and self-gravity equation. By using the code, we conducted a rotating supernova simulation. The Boltzmann solver provides the neutrino distribution functions essential to search for the electron lepton number zero-crossing, which announces the occurrence of fast flavor conversion (FFC) mode of the corrective neutrino oscillation. We report the finding of rotation-induced FFC in the neutrino heating region and discuss the reason.