  We present a dynamical (composite) axion model where the Peccei-Quinn (PQ)
symmetry arises automatically as a consequence of chirality and gauge symmetry.
The Standard Model is simply extended by a confining and chiral $SU(5)$ gauge
symmetry. The PQ symmetry coincides with a $B-L$ symmetry of the exotic sector.
The theory is protected by construction from quantum gravitational corrections
stemming from operators with mass dimension lower than nine.
