As a result of the disaster with the Japanese torpedo boat Tomatsuru a month ago due to an unstable design were 20 torpedo boats to be altered. Four of these boats were the Tomatsuru which was later salvaged and her sister ships Chidori, Manacuru and Hatsukari. These boats were armed with 5-12cm guns and 4 torpedo tubes and built as a result of the naval shipbuilding program on 1931. The building of the 16 other boats was projected in the second program. The changes were to be done without an decrease in the armament.
