Towards the end of 1943, in response to unfavorable progress in the war, the
Japanese high command heard suggestions for various suicide craft. These suggestions were initially rejected as "defeatist" but later deemed necessary. For the naval department this meant
kamikaze planes,
kaiten submarines,
fukuryu suicide divers or human
naval mines, and
shinyo suicide boats. The program began in March 1944. The first vessels were tested on 27 May, after which it was decided that the original steel hull design would be replaced by a wooden hull due to the Japanese steel shortage. On 1 August, 150 students, on average 17 years old, elected to begin training for the
Shinyo. The main operative use took place during the
Philippines Campaign of 1944–45. By September 1945, substantial numbers of these craft had been deployed to various locations throughout the Japanese Empire. Around 400 boats were transported to
Okinawa and
Formosa, and the rest were stored on the coast of Japan for the ultimate defense against the expected
invasion of the Home islands. In Hong Kong, several shinyo boats laden with explosives were discovered at
Sok Kwu Wan (Picnic Bay) on
Lamma Island, positioned and ready for deployment against Allied forces. ==Characteristics==