  By using an unbiased quantum Monte Carlo method, we investigate the hard-core
Bose-Hubbard model on a square lattice with anisotropic dipole-dipole
interaction. To study the effect of the anisotropy, dipole moments are assumed
to be polarized in the $y$ direction on the two-dimensional (2D) $xy$ plane. To
perform efficient simulations of long-range interacting systems, we use the
worm algorithm with an O(N) Monte Carlo method. We obtain the ground-state
phase diagram that includes a superfluid phase and a striped solid phase at
half-filling as two main phases. In addition to these two main phases, we find
a small region where there are multi plateaus in the particle density for small
hopping amplitudes. In this region, the number of plateaus increases as the
system size increases. This indicates the appearance of numerous competing
ground states due to frustrated interactions. In our simulations, we find no
evidence of a supersolid phase.
