  The next-generation water Cherenkov Hyper-Kamiokande detector will be able to
detect thousands of neutrino events from a galactic Supernova explosion via
Inverse Beta Decay processes followed by neutron capture on Gadolinium. This
superb statistics provides a unique window to set bounds on neutrino
properties, as its mass and lifetime. We shall explore the capabilities of such
a future detector, constraining the former two properties via the time delay
and the flux suppression induced in the Supernovae neutrino time and energy
spectra. Special attention will be devoted to the statistically sub-dominant
elastic scattering induced events, normally neglected, which can substantially
improve the neutrino mass bound via time delays. When allowing for a invisible
decaying scenario, the $95\%~$C.L. lower bound on $\tau/m$ is almost one order
of magnitude better than the one found with SN1987A neutrino events.
Simultaneous limits can be set on both $m_\nu$ and $\tau_{\nu}$, combining the
neutrino flux suppression with the time-delay signature: the best constrained
lifetime is that of $\nu_1$, which has the richest electronic component. We
find $\tau_{\nu_1}\gtrsim 4\times 10^5~$s at $95\%~$C.L. The tightest
$95\%~$C.L. bound on the neutrino mass we find is $0.34~$eV, which is not only
competitive with the tightest neutrino mass limits nowadays, but also
comparable to future laboratory direct mass searches. Both mass and lifetime
limits are independent on the mass ordering, which makes our results very
robust and relevant.
