  We study physics potential of Very Long Base-Line (VLBL) Neutrino-Oscillation
Experiments with the High Intensity Proton Accelerator, which will be completed
by the year 2007 in Tokai-village, Japan. As a target, a 100 kton-level
water-$\check {\rm C}$erenkov detector is considered at 2,100 km away. Assuming
the pulsed narrow-band $\nu_\mu$ beams, we study sensitivity of such
experiments to the neutrino mass hierarchy, the mass-squared differences, one
CP phase and three angles of the lepton-flavor-mixing matrix. We find that
experiments at a distance 2,100 km can determine the neutrino mass hierarchy if
the mixing matrix element $|U_{e3}|$ is not too small. The CP phase and
$|U_{e3}|$ can be constrained if the large-mixing-angle solution of the
solar-neutrino deficit is realized.
