The Wartime Naval Armaments Supplement Programme (マル戦計画, 昭和十八年度戦時艦艇建造計画, Maru Sen Keikaku, Shōwa-Jūhachi-Nendo Senji Kantei-Kenzō Keikaku) was the 1943-44 War Programme to fund the armaments expansion plan of the Imperial Japanese Navy (IJN).
Early 1944, the IJN started building warships for war. The plan did not include any large warships which were suitable for offensive operations.
| Category | Class | Vessel number(s) | Completed | Converted | Cancelled |
| Military transporter 2nd class | No.101 | #1501–1569 and 32 vessels | No.101 and 68 vessels | 22 vessels were transferred to the Army. | 32 vessels |
| Coast defence boat Type-A (steel) (jp:海防艇) | No.1 | #1701–1760 | |||
| Minelayer | Kamishima | #1801–1809 | Kamishima (#1801), Awashima (#1802) | #1803–1809 | |
| Minoo | #1821–1822 | Minoo (#1821) | #1822 | ||
| Coast defence boat Type-B (wood) (jp:海防艇) | No.101 | #1851–1870 | |||
| Auxiliary subchaser | Aux. No.1 | #2001–2100 | Aux. No.151 (#2001) to Aux. No.250 (#2100) | ||
| Auxiliary patrol boat | Aux. No.1 | #2121–2400 | Aux. No.1 (#2121) and 26 vessels | #2125–2144, 2148–2150, 2155–2156, 2159–2173, 2176–2183, 2187–2203, 2207–2209, 2214–2229, 2232–2241, 2244–2252, 2261–2271, 2277–2282, 2287–2292, 2302–2310 and 2314–2400 | |
| Escort ship Type-C | No.1 | #2401--2532 | No.1 (#2401) and 55 vessels | #2446--2447, 2450--2452, 2455--2502, 2505--2506, 2515--2532 and 168 vessels | |
| Escort ship Type-D | No.2 | #2701--2843 | No.2 (#2701) and 66 vessels | #2735, 2740, 2743--2750, 2754--2755, 2757, 2760--2761, 2764, 2768, 2770, 2773--2774, 2776, 2781--2792, 2794, 2803--2843 and 57 vessels | |
| Military transporter 1st class | No.1 | #2901--2922 and 12 vessels | No.1 (#2901) and 20 vessels | 12 vessels | |
| Submarine Type-D | I-361 | #2961 | I-372 (#2961) | ||
| I-373 | #2962--2967 | I-373 (#2962) | #2963--2967 | ||
| S60 | #2968--2971 | #2968--2971 | |||
| Submarine Type-E | S54-2 | #2981--3024 and 48 boats | #2981--3024 and 48 boats | ||
| Patrol torpedo boat | PT-151, PT-201, PT-220, PT-235, PT-241, PT-301, PT-327, PT-411, PT-468, PT-469, PT-474, PT-491, PT-538, H-2, H-10, H-27, H-74 and H-101 | 1540 vessels | approx. 860 vessels | unknown | |
| High-speed submarine (large) | I-201 | #4501--4506 | I-201 (#4501), I-202 (#4502), I-203 (#4503) | ||
| S56B | #4507--4523 | #4509--4523 | |||
| Transport submarine (small) | Ha-101 | #4601--4612 | Ha-101 (#4601), Ha-102 (#4602), Ha-103 (#4603), Ha-104 (#4604), Ha-105 (#4605), Ha-106 (#4606), Ha-107 (#4607), Ha-108 (#4608), Ha-109 (#4609), Ha-111 (#4611) |
#4610 and #4612 | |
| Escort ship Type-B | Ukuru | #4701–4721 | Inagi (#4701), Habushi (#4702), Ojika (#4703), Kanawa (#4704), Uku (#4705), Takane (#4707), Kuga (#4709), Shiga (#4711), Iō (#4712) |
#4706, #4708, #4710 and #4713–#4721 | |
| Destroyer Type-D | Matsu | #4801 - 4832 | Nire (#4809), Nashi (#4810), Sii (#4811), Enoki (#4812), Odake (#4814), Hatsuume (#4815) | #4801–4808, 4813 and 4816–4832 | |
| Fleet oiler | Hario | #4901–4904 | Hario (#4901) | #4902–4904 | |
| High-speed submarine (small) | Ha-201 | #4911–4989 | Ha-201 (#4911), Ha-202 (#4912), Ha-203 (#4913), Ha-204 (#4914), Ha-205 (#4915), Ha-207 (#4917), Ha-208 (#4918), Ha-209 (#4919), Ha-210 (#4920), Ha-216 (#4926) |
#4916, #4921 - #4925, #4927 - #4989 (of which 11 were launched and 16 more laid down; 42 cancelled before laying down{ |
This programme was projected only, and the vessels were never ordered.
| Category | Class | Quantity planned |
| High-speed submarine (large) | I-201 | 76 vessels |
| Submarine Type-D | I-373 | 140 vessels |
| Transport submarine (small) | Ha-101 | 88 vessels |
| High-speed submarine (small) | Ha-201 | 10 vessels |
| Escort ship Type-C | No.1 | 168 vessels |
| Escort ship Type-D | No.2 | 60 vessels |
