  We study the statistical mechanics for quantum scalar fields under the
multi-parameter rotating black hole spacetime in arbitrary D dimensions. The
method of analysis is general in the sense that the metric does not depend on
the explicit black hole solutions. The generalized Stefan-Boltzmann's law for
the scalar field is derived by considering the allowed energy region properly.
Then the generalized area law for the scalar field entropy is derived by
introducing the invariant regularization parameter in the Rindler spacetime.
The derived area law is applied to Kerr-AdS black holes in four and five
dimensions. Thermodynamic implication is also discussed.
