Ordinary differential system in dinension six with affine Weyl group symmetry of type $D_4^{(2)}$

We find a three-parameter family of ordinary differential systems in dimension six with affine Weyl group symmetry of type $D_4^{(2)}$. This is the second example which gave higher order Painlev'e type systems of type $D_4^{(2)}$. We show that we give its symmetry and holomorphy conditions. These symmetries, holomorphy conditions and invariant divisors are new.