  We report on the observations of two ultra metal-poor (UMP) stars with
[Fe/H]~-4.0 including one new discovery. The two stars are studied in the
on-going and quite efficient project to search for extremely metal-poor (EMP)
stars with LAMOST and Subaru. Detailed abundances or upper limits of abundances
have been derived for 15 elements from Li to Eu based on high-resolution
spectra obtained with Subaru/HDS. The abundance patterns of both UMP stars are
consistent with the "normal-population" among the low-metallicity stars. Both
of the two program stars show carbon-enhancement without any excess of heavy
neutron-capture elements, indicating that they belong to the subclass of
CEMP-no stars, as is the case of most UMP stars previously studied. The [Sr/Ba]
ratios of both CEMP-no UMP stars are above [Sr/Ba]~-0.4, suggesting the origin
of the carbon-excess is not compatible with the mass transfer from an AGB
companion where the s-process has operated. Lithium abundance is measured in
the newly discovered UMP star LAMOST J125346.09+075343.1, making it the second
UMP turnoff star with Li detection. The Li abundance of LAMOST
J125346.09+075343.1 is slightly lower than the values obtained for less
metal-poor stars with similar temperature, and provides a unique data point at
[Fe/H]~-4.2 to support the "meltdown" of the Li Spite-plateau at extremely low
metallicity. Comparison with the other two UMP and HMP (hyper metal-poor with
[Fe/H]<-5.0) turnoff stars suggests that the difference in lighter elements
such as CNO and Na might cause notable difference in lithium abundances among
CEMP-no stars.
