  Nakasuji, Phuksuwan, and Yamasaki defined the Schur multiple zeta values and
gave iterated integral expressions of the Schur multiple zeta values of the
ribbon type. This paper generalizes their integral expressions to the ones of
more general Schur multiple zeta values having constant entries on the
diagonals. Furthermore, we also discuss the duality relations for Schur
multiple zeta values obtained from the integral expressions.
