The Tamano yard lies on the Seto Inland Sea in Tamano, Okayama prefecture, and is operated by Mitsubishi Heavy Industries Maritime Systems Co., Ltd., a wholly owned MHI company that began trading on 1 October 2021 after MHI took over the naval and government ship business of Mitsui E&S Shipbuilding under an agreement signed on 29 March that year. The company is headquartered at the yard itself, has capital of 500 million yen and employs 419 people. Shipbuilding on the site goes back to 1917, when it opened as the shipbuilding department of the old Mitsui & Co. and completed its first ship, Kaisho Maru; it became Tama Shipyard in 1937 and Mitsui Engineering & Shipbuilding in 1942.
Ownership at Tamano is now split, and the distinction matters when placing an enquiry. MITSUI E&S Co., Ltd., renamed from Mitsui E&S Holdings in 2023, still runs a Tamano works in the same location, but for marine engines, port cranes and industrial machinery rather than ships. The commercial shipbuilding business passed to Tsuneishi in stages, 49 per cent in October 2021, 66 per cent in October 2022 and the remainder on 30 June 2025, and now trades from Tokyo as a design and engineering firm. Commercial newbuilding is no longer carried out at the yard.
The scope is new construction, repair and conversion of ships and of the equipment and systems installed in them, across three business lines: naval vessels, government ships, and special and underwater equipment. The underwater line covers surface and underwater vehicles, unmanned vehicle development from the surface down to the deep sea, marine hydraulic equipment and the self-propelled EMD mine disposal munition. Repair work has taken in bulk carriers, service vessels, fishing vessels and tugs, and design and engineering are offered in their own right.
The build record covers frigates and destroyers for the Japan Maritime Self-Defense Force, among them the Mogami-class Yubetsu and Kumano and the Akizuki-class Fuyuzuki, together with the replenishment ship Mashu, the submarine rescue ships Chiyoda and Chihaya, the Osumi-class transports and the Hibiki-class ocean surveillance ships. Japan Coast Guard patrol vessels of the Miyako, Kunigami and Bisan classes were built here, as were the Fisheries Agency research ship Kaiyo Maru, handed over in March 2023, the enforcement vessel Shirarei Maru, the training ships Toba Maru, Yuge Maru and Taisei Maru, and the Kobe University training ship Kaijin Maru, launched in October 2021 and awarded Ship of the Year 2022 in the fishing and research vessel category. The largest vessels the operator names for itself are the 221 metre Mashu and the 210 metre deep-sea drilling vessel Chikyu.
