I-156 was an older Kaidai cruiser submarine of the Imperial Japanese Navy. Built at Kure, she was launched on 23 March 1928 and commissioned on 31 March 1929 as I-56. On the day she entered service she was placed under the Kure Naval District.
On 1 April 1929 she joined Submarine Division 19. The division was then put into Submarine Squadron 2 of the 2nd Fleet, inside the Combined Fleet. Accounts differ on the timing: some put that squadron duty on 1 April 1929, and others on 30 November 1929. The division moved to the Kure Guard Squadron on 1 December 1931, then on 20 May 1932 went back to Submarine Squadron 2 in the 2nd Fleet.
She left Sasebo on 29 June 1933 with the rest of the squadron. Division 18 sent I-53, I-54, and I-55, and Division 19 sent I-57 and I-58 besides I-56. They trained off China and at Mako in the Pescadores and were in Takao, on Formosa, by 5 July. Leaving Takao on 13 July, they worked again in Chinese waters and reached Tokyo Bay on 21 August. On 25 August the six boats passed in review at Yokohama. On 27 September 1934 she sailed from Ryojun in Manchukuo with I-57, I-58, I-61, I-62, I-64, I-65, I-66, and I-67, trained off Qingdao, and the group was back at Sasebo on 5 October.
Division 19 returned to the Kure Guard Squadron on 15 November 1934. On 15 November 1935 it rejoined the Combined Fleet, assigned to Submarine Squadron 1 in the 1st Fleet. While I-56 was anchored in Kure harbor, a sudden gale on 18 December 1935 overturned her liberty boat at 06:50. The boat took her commanding officer and four engineers; after sunrise a single man from it was found alive. On 1 December 1936 the division came directly under the Kure Naval District. It dropped to the First Reserve on 7 January 1937, and I-56 was decommissioned that day. She seems to have been in commission again by 1 December 1937, and on 1 January 1938 she was once more assigned directly to the Kure Naval District. The division fell to the Third Reserve on 15 December 1938. She returned to active duty on 15 November 1939, when Division 19 joined Submarine Squadron 4 in the 1st Fleet, and on 15 November 1940 that squadron was placed directly under the Combined Fleet.
She had been completed in 1929 as I-56 and was renamed I-156 in May 1942. Zenji Orita commanded her before the middle of 1942. She was still afloat at the surrender and gave herself up in Japan. She was struck on 30 November 1945 and scuttled off the Goto Islands on 1 April 1946.