Kasashima-class salvage tugboat

The Kasashima-class salvage tugboats (笠島型救難船兼曳船,) were a class of rescue ship / tugboat of the Imperial Japanese Navy (IJN), serving during World War II. The IJN official designation for this class was 600-ton salvage tugboat (六〇〇瓲救難船兼曳船,) for all vessels.

Background
Under the Russo-Japanese War, the IJN purchased many steamships and converted them to salvage vessels. However, when they entered in 1930s, deterioration became remarkable. The IJN initially planned for the Tategami class to succeed them. The IJN was going to build the Tategami-class salvage tugboat one by one for three years from fiscal year 1936. However, the plan came to an impasse due to budget shortages by the second year. The IJN postponed building of the second ship for two years, and built two cheap 600-ton ships instead: the Hashima (later renamed Kasashima) and Futakami.