What Akasaka Diesels does

Akasaka Diesels (株式会社赤阪鐵工所), founded in 1910 and headquartered in Yaizu, Shizuoka Prefecture, Japan, is a publicly traded (Tokyo Stock Exchange: tyo:6022) manufacturer of marine diesel engines serving domestic and international shipowners, shipbuilders, and maritime operators. The company designs and produces proprietary 4-stroke marine diesel engines (AT, AX, A, K/E, AH, U series covering outputs from 749 kW to 3,309 kW) and manufactures 2-stroke UE engines (LSJ, LSH, LSII, LSE series) under license from Japan Engine Corporation (J-ENG), a core licensing relationship dating to 1955. Vertically integrated operations span a 1,000-ton/month casting facility, large-scale machining (up to 100 tons, L10m×W4.5m×H4.9m), and dedicated repair and service departments.

Revenue is generated across four streams: new marine engine hardware sales (proprietary 4-stroke and licensed 2-stroke), aftermarket service and parts through dedicated repair departments, biodiesel fuel (BDF) manufacturing from waste cooking oil launched November 2024, and contract casting/machining/industrial machinery for third-party customers including power generation, construction, and satellite antenna applications. The go-to-market is exclusively direct B2B sales through a regional office network in Tokyo, Yaizu, and Imabari, supported by an Overseas Sales Section. Products are customized for specific vessel types, with long, engineering-intensive sales cycles.

The company is actively repositioning its technology portfolio to address IMO 2050 net-zero emissions, with development underway across low-pressure SCR (NOx Tier III compliance, first domestic small 2-stroke implementation in 2019), LNG gas-only combustion (USE30G, ~25% CO₂ reduction), methanol dual-fuel (test engine 3X28Me completed October 2025 with dedicated experimental building), ammonia and hydrogen (via J-ENG technical agreement and SBH hydrogen consortium), bio-diesel fuel, and a self-backup engine for autonomous navigation. Additional non-marine offerings include the Nephron System lubricating oil purification line (expanded via 2023 acquisition), marine and commercial soundproof rooms (Malie / Malie Aina), and the AE-Dr. cloud-based engine data collection system.

Name

Akasaka Diesels

Legal name

株式会社赤阪鐵工所

Website

https://akasaka-diesel.jp

Company type

Public

Founded year

1910

Operating status

Operating

Headcount range

251–500 employees

Short description

Akasaka Diesels is a Japanese marine diesel engine manufacturer (founded 1910, TSE-listed) that designs proprietary 4-stroke engines and licensed 2-stroke UE engines for shipowners, shipbuilders, and maritime operators, with vertically integrated casting, machining, and aftermarket service capabilities.

Ownership category

akta.pro rank

Product category

Marine Diesel Engines

NAICS

Engine, Turbine, and Power Transmission Equipment Manufacturing (33361), Engine, Turbine, and Power Transmission Equipment Manufacturing (3336), Petroleum Bulk Stations and Terminals (424710), Motor Vehicle Gasoline Engine and Engine Parts Manufacturing (336310)

SIC

Engines & Turbines (3510), Wholesale-Petroleum & Petroleum Products (No Bulk Stations) (5172), Special Industry Machinery (No Metalworking Machinery) (3550)

akta.pro primary industry

Marine Diesel & Dual-Fuel Engines (IMAJAHAA)

akta.pro secondary industries

Fuel & Emissions Systems for Propulsion (Fuel supply, SCR, EGR, exhaust aftertreatment) (IMAJAHAK), Renewable Diesel (HVO/HEFA) Production (EUAAAHAD), Propulsion, Power & Energy Systems Design (Diesel, Hybrid, Electric, Alternative Fuels) (IMAJAGAE)

Keywords

• Marine diesel engines
• Ship propulsion systems
• Marine engineering
• Marine emissions control
• Industrial casting machining

Headquarters

HQ city

Tokyo

HQ country

Japan

HQ region

Asia

Offices6 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Personnel, Operations, Technology or R&D, Infrastructure, Supply Chain

Revenue model

1. Marine Diesel Engine Manufacturing and Sales: Manufacture and sale of 4-stroke marine diesel engines (proprietary Akasaka designs: AT, AX, A, K, E, AH, U types) and 2-stroke UE diesel engines under J-ENG license (LSJ, LSH, LSII, LSE types). Engines are installed on cargo ships, tankers, fishing vessels, coastal vessels, and various other maritime applications domestically and internationally.
2. Aftermarket Service, Parts, and Repair: After-sales service, spare parts supply, and repair services for marine engines through dedicated service departments (Repair Sales Section, Repair Service Section).
3. Bio-diesel Fuel (BDF) Manufacturing and Sales: New business launched in November 2024: manufacturing and selling bio-diesel fuel (BDF) refined from waste cooking oil (廃食油). Plant construction completed for BDF production.
4. Casting, Machining, and Industrial Machinery: Casting and machining of large industrial components (up to 10 tons per unit, up to L10m×W4.5m×H4.9m), industrial machinery, satellite antennas, automotive test equipment. Also custom development products and industrial machinery manufacturing.

Go-to-market motion1 record

Distribution channels4 records

Marketing channels5 records

Core offering

Akasaka Diesels manufactures and sells marine diesel engines — proprietary 4-stroke engines (TYPE AT, AX, A, K/E, AH, U) and licensed 2-stroke UE engines (TYPE LSJ/LSH, LSII, LSE) — for cargo ships, tankers, LPG carriers, fishing vessels, ferries, and government patrol boats. The company also provides the Nephron lubricating oil purification system, marine and commercial soundproof rooms (Malie, Malie Aina), large-scale casting and machining services, biodiesel fuel (BDF) from waste cooking oil, and after-sales service and repair. Sales are conducted direct through Tokyo, Yaizu, and Imabari sales offices, with engine customization for specific vessel types.

Product overview

Akasaka Diesels (株式会社赤阪鐵工所) is a marine diesel engine manufacturer established in 1910, offering a comprehensive portfolio centered on proprietary 4-stroke engines (TYPE AT, AX, A, K/E, AH, U series) and licensed 2-stroke UE engines (TYPE LSJ/LSH, LSII, LSE series) through Japan Engine Corporation. The company provides complete propulsion solutions for cargo ships, tankers, LPG carriers, fishing boats, and ferries. Beyond engines, Akasaka Diesels manufactures industrial machinery including the Nephron System (oil purification), marine and business soundproof rooms (Malie, Malie Aina), casting and machining products, and custom development products. Recent initiatives include methanol dual-fuel engine development, biodiesel fuel production, self-backup engine development for autonomous navigation, and SBH hydrogen generation technology. The company operates integrated production from casting and machining to final assembly, with facilities in Yaizu City, Shizuoka Prefecture.

Differentiator

Problem solved

Functional benefit

Brands

• ネフロンシステム (Nephron System): Oil purification device using centrifugal separator and proprietary Nephron filter dual structure for removing fine impurities from lubricating oil and fuel oil.

Products and services

• TYPE AT Engine (AT33/AT33L) Proprietary low-speed 4-stroke engine based on A/AX series with Miller cycle and bore cooling system. AT33: 1,499 kW at 260 min⁻¹; AT33L: 749 kW at 200 min⁻¹ for ultra-low fuel consumption. Used for main propulsion on cargo ships, tankers, and coastal vessels.
• TYPE AX Engine Medium-speed 4-stroke engine for weight reduction, compactness, fuel efficiency, and high reliability. Output: 1,176–1,912 kW at 260–320 min⁻¹ with ALS cylinder lubrication system. Used for cargo ships, tankers, and fishing vessels.
• TYPE A Engine Long-stroke 4-stroke engine developed for compactness and fuel efficiency. Output: 1,618–3,309 kW at 210–310 min⁻¹. Installed on cargo ships, tankers, and various maritime vessels.
• TYPE K/E Engine Energy-saving engine combined with reduction gear for fishing boats and fisheries high school training vessels. TYPE K: 956–1,471 kW at 370–420 min⁻¹; TYPE E: 1,323–1,618 kW at 450–470 min⁻¹.
• TYPE AH Engine Robust construction 4-stroke engine for overseas purse seine and high-speed fishing boats. Output: 2,942 kW at 350 min⁻¹ with 4-valve system and exhaust valve box.
• TYPE U Engine Single-engine single-shaft to twin-shaft multi-geared configuration engine for ferries and government patrol vessels. 85% of full output extractable from crankshaft front end. Output: 1,838–2,427 kW at 720 min⁻¹.
• TYPE LSJ/LSH Engine (UE Engine) Latest 2-stroke UE engine series achieving class-leading fuel efficiency for environmental compliance, manufactured under J-ENG license. TYPE LSJ: 2,000–6,960 kW at 118–167 min⁻¹; TYPE LSH: 1,775–10,080 kW at 85–230 min⁻¹. Used in cargo ships and chemical tankers.
• TYPE LSII Engine (UE Engine) High-performance 2-stroke UE engine incorporating LA/LS long-stroke power-saving features with latest technology and CAE-based compact, lightweight design. Output: 1,655–4,530 kW at 157–215 min⁻¹.
• TYPE LSE Engine (UE Engine) Environmentally compliant 2-stroke UE engine matching market requirements, also available as electronically controlled engine. Output: 2,000–11,040 kW at 96–167 min⁻¹.
• Nephron System (SR-Z series) Dual-structure oil purification system combining centrifugal separator (waterless clarifier method, removes 10 μm+ impurities) with proprietary Nephron filter (removes ~85% of residual impurities to under 1 μm). Available for marine engines, power generators, and vehicles. Models include SR-Z 30P-40HP, SR-Z 60P-60HP, SR-Z 60P-60HP-N, SR-Z 100PA-80HP, and SR-Z 040HP. Extends oil life and supports Carbon Neutral Port initiatives.
• Marine Soundproof Room Malie Marine soundproof room with type approval from Ministry of Land, Infrastructure, Transport and Tourism (June 2020) and ClassNK certification. Designed for noise reduction in marine vessel engine rooms.
• Business Use Soundproof Room Proprietary soundproof room developed and sold as a commercial business use product since August 2022.
• Malie Aina (Marine Panel-type Soundproof Floating Floor) Marine panel-type soundproof floating floor developed jointly with Hayakawa Rubber Co., Ltd. Sound insulation approval Rw=47dB from ClassNK and Ministry of Land, Infrastructure, Transport and Tourism.
• Casting Products Cast iron (FC250–FC350), ductile iron (FCD400–FCD600), and alloy cast iron (wear-resistant, heat-resistant, corrosion-resistant). Monthly production capacity 1,000 tons. Unit weight 100 kg–10 t; max dimensions L6m × W3m × H2m. Products include engine frames, pump discharge pipes, cylinder liners, and seismic isolation devices.
• Machined Products Machining services for castings, forgings, and fabricated parts using large 5-face machining centers. Max dimensions L10m × W4.5m × H4.9m; max weight 100 tons. Crankshaft machining up to 6,200mm length. Serves power generation, construction machinery, press machinery, pumps, and cylinder liner applications.
• Development Products Custom development products leveraging marine diesel engine technology. Includes automotive test equipment (propeller shaft testing machines, transmission testing machines), satellite antennas (QZSS), and factory equipment surface plates. Full production from design to assembly.
• AE-Dr. (Main Engine Data Collection System) Cloud-based main engine data collection and monitoring system for marine vessels. Provides customer login portal for engine telemetry and diagnostics.
• Biodiesel Fuel (BDF) Biodiesel fuel manufactured from waste cooking oil. New business launched November 2024 with plant construction completed for BDF production.

Quantifiable outcome

• IMO NOx Tier III compliance demonstrated through actual LP-SCR operation at Toyoda Factory in November 2019
• +3 more outcomes

Named customers2 records

Segments4 records

Ideal customer profiles4 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature8 records

Partnerships

Nine partnerships are on record, tiered secondary and core.

• 日本軽金属株式会社 (Nippon Light Metal Co., Ltd.)secondaryStrategic or Co-development Partner · 12 February 2026Three-company consortium partner in the development of an SBH (sodium borohydride) hydrogen generation device for small boats. As part of Shizuoka Prefecture's hydrogen technology initiative, the consortium developed an SBH fuel cell experimental vessel with sea trials completed.
• 三協テクノ株式会社 (Sankyo Technos Co., Ltd.)secondaryStrategic or Co-development Partner · 12 February 2026Three-company consortium partner in the development of an SBH (sodium borohydride) hydrogen generation device for small boats. Participated in the development of the SBH fuel cell experimental vessel under Shizuoka Prefecture's hydrogen initiative.
• 株式会社住本科学研究所 (Sumimoto Science Research Institute)secondaryTechnology or Integration · 25 September 2023Akasaka took over the manufacturing, sales, and maintenance business for lubricating oil/fuel oil management equipment from Sumimoto Science Research Institute via business transfer (事業譲受) effective September 25, 2023. This expanded Akasaka's Nephron System product line.
• 株式会社ジャパンエンジンコーポレーション (J-ENG)coreStrategic or Co-development Partner · 5 April 2023Strengthened cooperation with J-ENG through a new technical agreement for the development and popularization of next-generation low-carbon/decarbonization fuel UE engines capable of using ammonia fuel and hydrogen fuel as part of achieving a decarbonized society. Builds on the existing licensing relationship.
• イイノガストランスポート株式会社 (Iinogas Transport Co., Ltd.)secondaryStrategic or Co-development Partner · 23 October 2022Akasaka conducted a biofuel sea trial on October 23, 2022 using an AX33B main engine installed on Iinogas Transport's coastal LPG tanker 'Tokuhoumaru'. Iinogas provided the vessel for the trial of Akasaka's engine technology running on bio-fuel.
• 豊通エネルギー株式会社 (Toyotsu Energy Corporation)secondaryStrategic or Co-development Partner · 23 October 2022Participated in the October 2022 bio-fuel sea trial as a partner, providing support for the bio-fuel used in the trial on the Tokuhoumaru vessel equipped with Akasaka's AX33B engine.
• 早川ゴム株式会社 (Hayakawa Rubber Co., Ltd.)secondaryStrategic or Co-development Partner · 26 November 2021Joint development of the marine panel-type soundproof floating floor 'Malié Aina' (マーリエ・アイナ). Received sound insulation approval from ClassNK and Ministry of Land, Infrastructure, Transport and Tourism (Rw=47dB).
• 静岡県焼津市 (Yaizu City, Shizuoka Prefecture)secondaryStrategic or Co-development Partner · 13 September 2021Akasaka partnered with Yaizu City for a pilot program starting June 2026, supplying B5 diesel fuel (5% bio-diesel, 95% conventional diesel) for use in the city's official vehicles. Demonstrates the company's BDF production capability.
• 株式会社ジャパンエンジンコーポレーション (J-ENG / Japan Engine Corporation)coreOEM/ Whitelabel/ Licensing Partner · 1 January 1935Akasaka has manufactured 2-stroke UE diesel engines under license from J-ENG (which inherited the UE engine business from Mitsubishi Heavy Industries) since 1959. This partnership forms a core pillar of the company's marine engine business, covering large-bore 2-stroke engines (LSJ, LSH, LSII, LSE series) for ocean-going vessels. License agreement was renewed in March 2026 for UE engines (pure domestic marine low-speed engines).

Scale indicators5 records

Recent moves7 records

Expansion highlights6 records

Direct peers

• Caterpillar Marine (MaK): Produces medium-speed 4-stroke marine engines for propulsion and auxiliary use. Comparable to Akasaka's AX series and broader medium-speed portfolio in commercial shipping and offshore applications.
• Wärtsilä: Finnish manufacturer of 4-stroke marine engines and dual-fuel propulsion systems. Comparable to Akasaka's proprietary 4-stroke portfolio (AT, AX, A series) and competes on alternative fuel readiness (LNG, methanol, ammonia, hydrogen).
• MAN Energy Solutions: Global market leader in large 2-stroke marine diesel engines (including the legacy B&W license). Directly comparable to Akasaka's 2-stroke UE engine business and competes head-to-head in the ocean-going vessel main propulsion segment.
• Yanmar: Japanese manufacturer of marine and industrial engines with strong domestic and Asia-Pacific presence. Comparable to Akasaka across fishing, coastal, and small commercial segments, with overlapping 4-stroke product lines.
• Daihatsu Diesel: Japanese marine diesel engine maker focused on small to medium-bore marine engines. Closest direct domestic peer to Akasaka in coastal, fishing, and small ocean-going vessel segments.
• Niigata Power Systems: Japanese manufacturer of marine engines and gas/diesel engines for power generation. Domestic peer with overlapping 4-stroke medium-speed engine portfolio serving similar Japanese shipowner and fishing vessel customers.
• Bergen Engines: Norwegian manufacturer of medium-speed marine and offshore engines with focus on gas and dual-fuel propulsion. Comparable to Akasaka's USE30G LNG gas engine and methanol DF development programs.

Broad incumbents

• Rolls-Royce Power Systems (mtu): Produces medium and high-speed marine engines and integrated propulsion systems. Overlaps with Akasaka's medium-speed engine lines and competes in naval, commercial, and yacht segments under the mtu brand.
• Mitsubishi Heavy Industries (Marine): Parent of Japan Engine Corporation (J-ENG), from whom Akasaka licenses 2-stroke UE engines. A broad incumbent in marine machinery, also competing in the same 2-stroke space historically and shaping the technology roadmap Akasaka accesses via license.

Emerging players

• Hyundai Heavy Industries (HD Hyundai): Korean shipbuilder expanding into in-house marine engine production and alternative fuel propulsion. A vertically integrated emerging player whose engine ambitions overlap with Akasaka's licensed 2-stroke and next-fuel roadmaps.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights7 records

Customer concentration

• Instagraminstagram.com/akasaka_diesel
• LinkedInlinkedin.com/company/akasaka-diesels-ltd.

Revenue estimate

Valuation estimate

Number of profiles

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Akasaka Diesels