Industry Halts, Supply Chains Seize — How the Strait of Hormuz Blockade Is Breaking Japan's Industrial Structure

Originally Published in Japanese: March 25, 2026 / Last updated: April 2, 2026

1. Plastics… Food… A Distant War Shaking Japan's Daily Life
2. It's Not Just Fuel: Japan's Oil-Dependent Economy
3. Material and Energy Supply Chains: The Layers Above Manufacturing's SC
3.1. Material Supply Chain: The Naphtha That Sustained Japanese Life Is Running Out
3.2. Energy Supply Chain: The Price Japan Pays for Delayed Diversification
4. What Has Japan Been Missing?

Plastics… Food… A Distant War Shaking Japan's Daily Life

On February 28, 2026, the United States and Israel launched strikes against Iran. The resulting blockade of the Strait of Hormuz is now producing concrete effects on Japan's economy. In the petrochemical sector, reports indicate that production cuts of ethylene — the raw material for plastics — have begun.

Mitsubishi Chemical Corporation has started cutting ethylene production at its Ibaraki plant. Idemitsu Kosan Co.,Ltd. has notified customers of the possibility of suspending ethylene production. In Singapore, Sumitomo Chemical's group company declared force majeure not only on ethylene but also on acrylic resin feedstock.
"Petrochemical Plant Cuts, Logistics Material Shortage Looming in April" — March 9, 2026, Logistics Today
[Translated by QA+]

Idemitsu Kosan Co.,Ltd. announced on the 16th that it has begun reducing production of the basic chemical "ethylene" at its complexes in Chiba and Yamaguchi prefectures. The company cited concerns that procurement of the raw material naphtha (crude gasoline) may be disrupted due to the de facto blockade of the Strait of Hormuz. Idemitsu has not disclosed the timing or scale of the reduction. The company had already notified customers of the possibility of halting operations, but stated it has "not yet decided to stop" (company spokesperson).
"Idemitsu Also Cuts Ethylene Production in Chiba and Yamaguchi, Following Mitsubishi Chem and Mitsui Chemicals" — March 16, 2026, 15:58, Yuda Tomoda, The Asahi Shimbun
[Translated by QA+]

The impact extends beyond petrochemicals. On March 12, 2026, YAMAYOSHI SEIKA Co.,LTD., a confectionery manufacturer, released a statement announcing a temporary halt in factory operations and the possibility of delivery delays and shipment suspensions.

Due to the current international situation, the Strait of Hormuz has been blockaded, making it extremely difficult for us to procure the heavy oil used in our manufacturing processes. As a result, we deeply regret to announce that we are compelled to temporarily suspend factory operations, and there is a possibility that delays or suspensions in the supply of some products may occur.
"Important Notice Regarding Product Supply" — March 12, 2026, YAMAYOSHI SEIKA Co.,LTD.
[Translated by QA+]

On March 23, 2026, the company issued a further statement announcing the resumption of operations after securing a fuel supply.

We are pleased to inform you that fuel oil supply arrangements have been secured, and factory operations will resume on Monday, March 23, with product supply to follow in stages. We sincerely apologize for the significant inconvenience caused during the suspension period, and are deeply grateful for your understanding and warm words of encouragement. Please note that for some products, shipment volume adjustments may continue for a period following resumption. We remain committed as a company to ensuring stable supply going forward, and ask for your continued understanding.
"Notice of Operations and Product Supply Resumption" — March 23, 2026, YAMAYOSHI SEIKA Co.,LTD.
[Translated by QA+]

Approximately 70% of Japan's oil imports traveled via the route from the Persian Gulf, through the Strait of Hormuz, across the Indian Ocean, through the Malacca Strait, and into the South China Sea toward Japan. (Japan's overall dependence on Middle Eastern oil stands at approximately 90–95%.) A bottleneck that most people never thought about has been suddenly made visible — and it is already delivering impacts to Japan's domestic supply chains with almost no lead time.

It's Not Just Fuel: Japan's Oil-Dependent Economy

When people think of petroleum products, gasoline and diesel for automobiles tend to come to mind first. But oil also yields LPG, kerosene (which also becomes jet fuel), and heavy oil (used as fuel for large ships and as a heat source for boilers).

There is one more product generated in the refining process: naphtha. While naphtha is used as a fuel in some applications, a portion is sent to petrochemical manufacturers where it is used to produce ethylene — the feedstock for synthetic resins (plastics). Food packaging films, PET bottles, detergent containers, car bumpers, pharmaceutical packaging — nearly all of these everyday items are made from synthetic resins derived from ethylene. "Oil stopping" means not only that gasoline becomes unavailable, but that the plastic products indispensable to daily life can no longer be manufactured.

Within approximately three weeks of the Strait of Hormuz blockade, reports indicate that half of Japan's 12 domestic ethylene production facilities have moved to reduced output.

To conserve naphtha stocks, at least 6 of the 12 domestic ethylene production facilities are operating at reduced capacity.
"Ethylene Production: Focus Shifts to Post-May as April Operations Maintained; Mid-Stream Material Price Hikes Continue" — March 24, 2026, 18:10 (updated 19:12), Nikkei
[Translated by QA+]

On March 17, the Japan Petrochemical Industry Association (JPCA) issued the following statement:

Inventory levels for major petrochemical products are sufficient to cover approximately 3.5 to 4 months of domestic demand, and we recognize that a situation of immediate supply difficulty has not arisen.
"Comment from the Japan Petrochemical Industry Association Regarding the Persian Gulf Situation" — March 17, 2026 (Reiwa 8),
Japan Petrochemical Industry Association (JPCA)
[Translated by QA+]

Whether one reads this as "there's still enough" or "only 3–4 months left" changes the picture entirely. As of March 24, the JPCA indicated that facility operations can be maintained through April.

JPCA Chairman Kudo stated: "Each company is working hard to keep operations running through the Golden Week holidays in May." He added that while the situation varies by facility, operations overall can be maintained through April, and that "under the current circumstances, the top priority is ensuring supply is not cut off and keeping operations running as long as possible."
"Ethylene Production: Focus Shifts to Post-May as April Operations Maintained; Mid-Stream Material Price Hikes Continue" — March 24, 2026, 18:10 (updated 19:12), Nikkei
[Translated by QA+]

Japan also depends on the Middle East for LNG imports, among other resources. The Strait of Hormuz is truly Japan's lifeline — and it has proven to be the critical bottleneck in Japan's energy supply.

Material and Energy Supply Chains: The Layers Above Manufacturing's SC

Manufacturing rests on a complex, interwoven supply chain. Modern industrial products are composed of diverse materials involving many specialized producers. It is impossible for any single company today to handle everything from upstream to downstream. While multiple processing methods may be internalized, the procurement of raw materials — and above all, energy — is an undertaking that operates at the level of national strategy.

Material Supply Chain: The Naphtha That Sustained Japanese Life Is Running Out

The ethylene refined from naphtha — and the synthetic resin materials produced further downstream — achieve low costs through large-scale production, enabling broad distribution at prices accessible to the general public. The resin materials used in products are one thing, but packaging materials and the inks used to print on them are items that consumers discard upon opening (though their cost is naturally embedded in the product price), making them candidates for cost reduction.

Large-scale plants achieve cost stability and equipment maintenance by keeping utilization rates consistently high. Such facilities require continuous operation to maintain product quality and minimize equipment degradation. They cannot simply be shut down at the end of a workday and restarted each morning. In other words, resin products depend on a match between a stable consumption pace and a stable production pace to enable steady operations and steady distribution. Injection molding and other downstream processors of resin products must also manage utilization rates carefully, though they are more adaptable to fluctuations than plants themselves (this is not to say that such fluctuations are economically painless for those businesses). The stable production, use, and maintenance of resin materials is critically important for Japan to sustain its industrial base as a nation.

Energy Supply Chain: The Price Japan Pays for Delayed Diversification

The energy supply chain is of even greater importance. Locations where fossil fuels such as oil and LNG can be extracted are limited across the globe. Even where extraction is possible, raising the quality to a level usable by humans often requires enormous cost, and there are many cases where it simply is not economically viable — which is precisely why Japan has long depended on Middle Eastern oil.

Electricity, on the other hand, can be generated without dependence on fossil fuels. The options are nuclear power and renewable energy, each with its own advantages and disadvantages. Nuclear power offers large-scale generation capacity, but once a reactor is in operation, rapid changes in output are difficult, making flexible adjustment to demand challenging. It also carries significant risk in the event of an accident, along with high management costs. Renewable energy carries smaller risks and more limited impact in the event of failure, but generation capacity is small and output is unstable. Furthermore, in thinking about nuclear power in the context of the Iran situation, it is important to understand that the depletion of oil or LNG — and the resulting generation shortfall — does not mean that a halted reactor can simply be restarted on demand.

The construction of an energy portfolio — determining the origin and composition of energy sources — is the very foundation of a nation's economic security.

What Has Japan Been Missing?

As described above, the procurement of energy and the raw materials needed for manufacturing constitutes social infrastructure and the core of national strategy. That core has been shaken by a single action taken by the United States, Japan's own ally. The situation makes it clear that diversification of fossil fuel procurement and the construction of a power generation portfolio (along with the technological development required to achieve it) have been insufficient. Japan's sea lane defense has been primarily oriented toward the South China Sea and East China Sea — but who foresaw that the blockage would occur at a far more fundamental point: the Strait of Hormuz itself?

On March 19, 2026, led by the United Kingdom, Europe and Japan issued a coordinated statement.

We condemn in the strongest terms recent attacks by Iran on unarmed commercial vessels in the Gulf, attacks on civilian infrastructure including oil and gas installations, and the de facto closure of the Strait of Hormuz by Iranian forces.

We express our deep concern about the escalating conflict. We call on Iran to cease immediately its threats, laying of mines, drone and missile attacks and other attempts to block the Strait to commercial shipping, and to comply with UN Security Council Resolution 2817.

Freedom of navigation is a fundamental principle of international law, including under the United Nations Convention on the Law of the Sea.
Joint statement from the leaders of the United Kingdom, France, Germany, Italy, the Netherlands, Japan, Canada and others on the Strait of Hormuz March 19, 2026 Ministry of Foreign Affairs of Japan

The "fundamental principle" cited in the statement has long been recognized as something all nations must uphold. Yet did the states involved in the current tensions truly not recognize it?

What the current situation demonstrates is this: no matter how widely a principle is recognized as common understanding, it can be ignored when circumstances demand it. Security (= risk hedging) is not achieved by upholding shared norms alone. What is being asked of us now is whether, when those norms are violated, our own country — our own society — can sustain itself.

What has Japan truly lost during the era known as the "Lost Thirty Years"?

Japan once led the world industrially — a nation of a fraction of the global population that, through a language spoken nowhere else on earth, built a culture entirely its own. That culture has been replaced by an instability in which our own lives and livelihoods can be easily disrupted by shifts in the circumstances of other nations.

What have we created in the intervening decades? Or what should we have created? Is this a problem that politics alone can resolve? Now, more than ever, seems the time for those of us living in Japan to place a hand over our hearts and reflect — to reexamine the ground beneath our own feet.

To understand why this structure came to be, and what can be done from here — continue to Part 2.

The Strait of Hormuz Blockade Has Exposed Japan's "Single Point of Failure" — Resource Dependency Structure and the Path Forward

Originally Published in Japanese: April 2, 2026 Naphtha and LNG Shortages Are Now Visible As of April 2026, the blockade of the Strait of Hormuz — triggered by U.S. and Israeli strikes on Iran and Iran's subsequent retaliation — remains unresolved. While crude oil shortages were the primary concern in the early stages, the prolonged […]

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著者プロフィール

Takahiro Yoshida株式会社コルプ代表 / QA+編集長 Founder & CEO, QUALP Inc. / Editor-in-Chief, QA+

Takahiro Yoshida began his career in quality assurance at a precision equipment manufacturer in 2008, accumulating over 9 years of hands-on experience across mechanical hardware and embedded firmware. He led quality improvement initiatives in close collaboration with design and development teams, achieving measurable defect reduction through both process-stage quality building and mass-production-oriented approaches.
In 2018, he founded QUALP Inc., where he serves as Representative Director. Through the company's consulting arm, he supports small and medium-sized manufacturers in building organizational structures that reduce latent defect risk and absorb unforeseen cost pressures—drawing directly on his manufacturing floor experience to drive practical, lasting change.
He also runs QA+, a media platform for those who navigate the future through sound judgment and structural thinking.