  In 1980, detecting the evidence of the so-called Grand Unified Theory (GUT)
became a major challenge for experimentalists. The GUT predicted that protons
would decay, and M. Koshiba proposed the Kamioka Nucleon Decay Experiment
(Kamiokande), which was originally conceived and designed for the detection of
proton decay signals. This article describes the story of the Kamiokande
experiment from the preparation stage to the observation of the first candidate
events for proton decays.
