  We report the optical identification of the hardest X-ray source (AX
J131501+3141) detected in an unbiased wide-area survey in the 0.5--10 keV band,
the ASCA Large Sky Survey. The X-ray spectrum of the source is very hard and is
well reproduced by a power-law component (Gamma = 1.5^+0.7_-0.6) with N_H =
6^+4_-2 *10^22 cm^-2 (Sakano et al. 1998). We have found a galaxy with R=15.62
mag near the center of the error circle for the X-ray source. The optical
spectrum of the galaxy shows only narrow emission lines whose ratios correspond
to those of a type 2 Seyfert galaxy at z = 0.072, implying an
absorption-corrected X-ray luminosity of 2*10^43 erg sec^-1 (2--10 keV) and M_B
= -20.93 mag. A radio point source is also associated with the center of the
galaxy. We thus identify the X-ray source with this galaxy as an obscured AGN.
The hidden nature of the nucleus of the galaxy in the optical band is
consistent with the X-ray spectrum. These results support the idea that the
obscured AGNs/QSOs contribute significantly to the cosmic X-ray background in
the hard band at the faint flux level.
