  We investigate the parity-broken phase (Aoki phase) for staggered-Wilson
fermions by using the Gross-Neveu model and the strong-coupling lattice QCD. In
the both cases the gap equations indicate the parity-broken phase exists and
the pion becomes massless on the phase boundaries. We also show we can take the
chiral and continuum limit in the Gross-Neveu model by tuning mass and
gauge-coupling parameters. This supports the idea that the staggered-Wilson
fermions can be applied to the lattice QCD simulation by taking a chiral limit,
as with Wilson fermions.
