  The Tokai-to-Kamioka-and-Korea (T2KK) neutrino oscillation experiment under
examination can have a high sensitivity to determine the neutrino mass
hierarchy for a combination of relatively large (\sim 3.0^circ) off-axis angle
beam at Super-Kamiokande (SK) and small (\sim 0.5^circ) off-axis angle at L
\sim 1,000km in Korea. We elaborate previous studies by taking into account
smearing of reconstructed neutrino energy due to finite resolution of electron
or muon energies, nuclear Fermi motion and resonance production, as well as the
neutral current \pi^0 production background to the nu_mu to nu_e oscillation
signal. It is found that the mass hierarchy pattern can still be determined at
3sigma level if sin^22thata_rct \quiv 4|U_{e3}|^2(1-|U_{e3}|^2) \gsim
0.08(0.09) when the hierarchy is normal (inverted) with 5 \times10^{21} POT
exposure, or 5 years of the T2K experiment, if a 100kton water cherenkov
detector is placed in Korea. The \pi^0 backgrounds deteriorate the capability
of the mass hierarchy determination, whereas the events from nuclear resonance
productions contribute positively to the hierarchy discrimination power. We
also find that the \pi^0 backgrounds seriously affect the CP phase measurement.
Although \delta_mns can still be constrained with an accuracy of \sim \pm
45^circ (\pm 60^circ) at 1sigma level for the normal (inverted) hierarchy with
the above exposure if sin^22theta_rct \gsim 0.04, CP violation can no longer be
established at 3sigma level even for delta_mns=\pm 90^circ and
sin^22theta_rct=0.1. About four times higher exposure will be needed to measure
delta_mns with \pm 30^circ accuracy.
