  In this paper, we discuss physics potential of the Very Long Base-Line (VLBL)
Neutrino-Oscillation Experiments with the High Intensity Proton Accelerator
(HIPA), which is planned to be built by 2006 in Tokaimura, Japan.
  We propose to use conventional narrow-band \nu_\mu beams (NBB) from HIPA for
observing the \nu_\mu \to \nu_e transition probability and the \nu_\mu survival
probability.
  The pulsed NBB allows us to obtain useful information through counting
experiments at a huge water-Cherenkov detector which may be placed in our
neighbor countries.
  We study sensitivity of such an experiment to the neutrino mass hierarchy,
the mass-squared differences, the mixing angles and the CP phase of the 3\times
3 lepton flavor mixing matrix (MNS matrix).
  The CP phase can be measured with a 100kt detector if both the mass-squared
difference and U_{e3} elements of the MNS matrix are sufficiently large.
