  Imaging the vicinity of a black hole is one of the ultimate goals of VLBI
astronomy. The closest massive black hole, Sgr A*, located at the Galactic
center, is the leading candidate for such observations. Combined with recent
VLBI recording technique and submillimeter radio engineering, we now have
sufficient sensitivity for the observations. Here we show performance
simulations of submillimeter VLBI arrays for imaging Sgr A*. Good images are
obtained from submillimeter VLBI arrays in the southern hemisphere composed of
more than 10 stations. We also note that even with a small array, we can
estimate the shadow size and then the mass of the black hole from visibility
analysis. Now, all we need is to construct a submillimeter VLBI array in the
southern hemisphere if we wish to unveil the black hole environment of Sgr A*.
Key words: black hole, event horizon, Sgr A*, submillimeter
