  Recently, Maesaka, Seki and Watanabe discovered a surprising equality between
multiple harmonic sums and certain Riemann sums which approximate the iterated
integral expression of the multiple zeta values. In this paper, we describe the
formula corresponding to the multiple zeta-star values and, more generally, to
the Schur multiple zeta values of diagonally constant indices. We also discuss
the relationship of these formulas with Hoffman's duality identity and an
identity due to Kawashima.
