Submarines of the Imperial Japanese Navy
In 1904 Kawasaki Dockyard Company purchased plans for a modified version directly from Holland, and built two boats (Hulls No. 6 and 7), with the help of two American engineers, Chase and Herbert, who had been assistants to Holland. The Kawasaki-type submarines displaced 63 and 95 tons when submerged, and measured in overall length, respectively. both vessels measured at the beam. This contrasted with the original five imported Hollands-type submarines which had arrived that same year, at over 100 tons submerged, in overall length and beam. The Kawasaki Type #6 and #7 submarines had gained extra speed and reduced fuel consumption by . However both boats could launch only one torpedo, and each was manned by 14 sailors, whereas the imported Holland-type submarines could fire two torpedoes and could be operated by 13 sailors. This new type was designated the Type 6 submarine by the Imperial Japanese Navy, and was used primarily for test purposes.
Japanese submarine I-15
I-15 was a Japanese B1 type submarine. She was completed at Kure Navy Yard on September 30, 1940, whereupon she entered into service with the Imperial Japanese Navy. Her first and only commanding officer was Commander Nobuo Ishikawa. "I-15" operated off the north coast of Oahu during the raid on Pearl Harbor. Her second wartime patrol, in May and June 1942, took her to the Aleutians, where she conducted reconnaissance of several islands. "I-15"s third and final patrol took place from August to November 1942, when she operated in the Solomon Islands in the South Pacific, supporting the Japanese efforts to hold Guadalcanal. One source (Morison) suggests that "I-15" hit the battleship with a torpedo on September 15, 1942. More recent authorities (Hackett & Kingsepp) maintain that the torpedo came from another submarine operating in the area, , which was also responsible for the sinking of , which "I-15" duly observed and reported. On November 10, 1942, a U.S. ex-destroyer (modified to a fast minesweeper), , sank "I-15" at Cape Recherche, San Cristóbal, with all hands lost.
Commander Ishikawa was promoted to the rank of Captain posthumously. On December 14, 1942, more than one month after "I-15" was sunk, sank an unknown submarine which it misidentified as the "I-15".