  We present properties of moderately massive clusters of galaxies detected by
the newly developed Hyper Suprime-Cam on the Subaru telescope using weak
gravitational lensing. Eight peaks exceeding a S/N ratio of 4.5 are identified
on the convergence S/N map of a 2.3 square degree field observed during the
early commissioning phase of the camera. Multi-color photometric data is used
to generate optically selected clusters using the CAMIRA algorithm. The optical
cluster positions were correlated with the peak positions from the convergence
map. All eight significant peaks have optical counterparts. The velocity
dispersion of clusters are evaluated by adopting the Singular Isothemal Sphere
(SIS) fit to the tangential shear profiles, yielding virial mass estimates,
M500c, of the clusters which range from 2.7x10^13 to 4.4x10^14 solar mass. The
number of peaks is considerably larger than the average number expected from
LambdaCDM cosmology but this is not extremely unlikely if one takes the large
sample variance in the small field into account. We could, however, safely
argue that the peak count strongly favours the recent Planck result suggesting
high sigma8$value of 0.83. The ratio of stellar mass to the dark matter halo
mass shows a clear decline as the halo mass increases. If the gas mass
fraction, fg, in halos is universal, as has been suggested in the literature,
the observed baryon mass in stars and gas shows a possible deficit compared
with the total baryon density estimated from the baryon oscillation peaks in
anisotropy of the cosmic microwave background.
