  A Galactic supernova (SN) axion signal would be detected in a future neutrino
Mton-class water Cherenkov detector, such as the proposed Hyper-Kamiokande in
Japan. The main detection channel for axions is absorption on the oxygen nuclei
in the water. The subsequent oxygen de-excitation leads to a potentially
detectable gamma signal. In this contribution we present a calculation of the
SN axion signal and discuss its detectability in Hyper-Kamiokande.
