  We show that the phase boundary between the paramagnetic metal and the
nonmagnetic Mott insulator for the Hubbard model on a triangular lattice
obtained by Yoshioka et al. in arXiv:0811.1575 does not correctly represent
that of the thermodynamic limit but is an artifact of the 6 by 6 lattice they
rely on. After the system size extrapolation, the phase boundary is located at
U/t=5.2 as proposed by Morita et al., J. Phys. Soc. Jpn. 71 (2008) 2109 and in
contrast to Yoshioka et al. Here, U is the onsite Coulomb repulsion and t is
the nearest-neighbor transfer.
