  We determined chemical abundances of the Extremely Metal-Poor (EMP) star
S15-19 ([Fe/H]=-3.0) in the Sextans dwarf galaxy. While heavy neutron-capture
elements (e.g., Ba) are generally deficient in EMP stars in dwarf galaxies,
this object was shown to have an exceptional over-abundance of Ba ([Ba/Fe]
+0.5) by a previous study, which is similar to those of r-process-enhanced
stars found in the field halo. Our new high-resolution spectroscopy for this
object for the blue region, however, reveals that no clear excess of r-process
elements, like Eu, appears in this object. Moreover, a significant excess of
carbon ([C/Fe]= +1.0) and a deficiency of Sr ([Sr/Fe] = -1.4) are found for
this object. Taking the variation of radial velocities measured at the two
different epochs into consideration, the origin of the excesses of heavy
neutron-capture elements in S15-19 is not the r-process, but is the s-process
in an asymptotic giant branch (AGB) star that was the binary companion
(primary) of this object. Carbon- and s-process-enhanced material should have
been transferred to the surface of S15-19 across the binary system. These
results are compared with carbon-enhanced metal-poor stars in the field halo.
