I-351-class submarine
 The I-351-class submarine (伊三百五十一型潜水艦 I-351-gata sensuikan) was a class of tanker/transport submarines built for the Imperial Japanese Navy (IJN) during World War II. The IJN called this type of submarine Sen-Ho (潜補 Sensuikan-Hokyū Submarine-Tanker). The IJN designed these submarines to support flying boats in forward areas. By the time the first submarine was finished this capability was no longer needed and she was converted into an oil tanker.