  While the quantum Hall effect in graphene has been regarded as a realization
of the anomaly associated with the massless Dirac particle carrying half the
usual topological integer, this is hidden due to the doubling of the Dirac
cones. In order to confirm the half-integer contribution from each Dirac cone,
here we theoretically consider a lattice model in which the relative energy
between the two Dirac points is systematically shifted. With an explicit
calculation of the topological (Chern) number, we have demonstrated that each
Dirac cone does indeed contribute to the Hall conductivity as the half odd
integer series (... -3/2, -1/2, 1/2, 3/2, ...) when the Fermi energy traverses
the (shifted sets of) Landau levels. The picture is also endorsed, via the
bulk-edge correspondence, from the edge mode spectrum for the present model.
