  We study the system of a massive fermion field confined between two parallel
plates, where the properties of both plates are discussed under chiral MIT
boundary conditions. We investigate the effects of the chiral angle on the
Casimir energy for a massive fermion field with the general momentum. We find
that the Casimir energy as a function of the chiral angle is generally
symmetric, and the attractive Casimir force in the chiral case is stronger than
that in the nonchiral case. In addition, we investigate the approximate Casimir
energy for light and heavy mass cases. The behavior of the discrete momentum
and changes of spin orientation are also discussed.
