We propose the Hyper-Kamiokande (Hyper-K) detector as a next generation<br />
underground water Cherenkov detector. It will serve as a far detector of a long<br />
baseline neutrino oscillation experiment envisioned for the upgraded J-PARC,<br />
and as a detector capable of observing -- far beyond the sensitivity of the<br />
Super-Kamiokande (Super-K) detector -- proton decays, atmospheric neutrinos,<br />
and neutrinos from astronomical origins. The baseline design of Hyper-K is<br />
based on the highly successful Super-K, taking full advantage of a well-proven<br />
technology. (to be continued)