Japan Open Chain Announces Mainnet Migration Schedule for the "Tokyo Hard Fork"

– All Testing Complete; Countdown Begins to "The Merge" on November 27 –

Japan Blockchain Foundation, Co., Ltd. (Head office: Shibuya-ku, Tokyo; Representative: Daimei Inaba, hereinafter "the Company"), the operator and administrator of the consortium behind Japan Open Chain (JOC), a fully Ethereum-compatible public blockchain co-operated by Japanese enterprises, is pleased to announce that it plans to carry out Phase 1, "The Merge," of the "Tokyo Hard Fork" — the largest protocol upgrade since the network's launch — on the mainnet at around noon (JST) on November 27, 2026.

Following the completion of the testnet migration on September 7, 2026, all of the tests required for the production migration have been completed, and the mainnet Beacon Chain began operating on September 18. After these preparations and verifications, we are now announcing the implementation schedule.

To ensure a safe migration, external access to both the old and new chains will be temporarily restricted for approximately 30 minutes before and after The Merge (approximately 1 hour in total). During this period, block production will continue, but transaction processing will be suspended. For details, please see "For JOC Users" below. *The above plan is subject to change without notice depending on circumstances.

In preparation for The Merge, we have also published an official countdown page where you can check the network's progress and the estimated time of arrival in real time.

Tokyo Hard Fork Countdown Page: https://joc-website-preview.vercel.app/tokyo-hardfork/

With the Tokyo Hard Fork, JOC will move from its current PoA (Proof of Authority) to PoSA (Proof of Staked Authority), which is based on Ethereum's PoS, improving compatibility with Ethereum and strengthening network governance.

◽️ Tokyo Hard Fork Implementation Schedule

The Tokyo Hard Fork is a large-scale protocol upgrade that overhauls JOC's consensus mechanism.

JOC completed the testnet migration on September 7, 2026, and has been verifying the various functions and behaviors required for the hard fork. Having cleared all test items, we have decided on the mainnet implementation schedule.

The progress to date and the upcoming schedule are as follows.

Date	Description
September 7, 2026	Testnet migration completed
September 18, 2026	Mainnet Beacon Chain begins operating
Around noon on November 27, 2026 (planned)	Mainnet Phase 1 "The Merge"

As with the upgrade Ethereum carried out in 2022, The Merge will be executed automatically when the network's cumulative difficulty (Total Difficulty) reaches a preset threshold (Terminal Total Difficulty, hereinafter "TTD"). The TTD has been set to "47,370,500" this time.

Because the actual execution time will vary depending on the network's progress, we will publish the latest estimated time on the official countdown page as needed.

◽️ From Beacon Chain Launch to "The Merge"

JOC has been moving to the new consensus mechanism in stages while keeping the existing network running stably.

On September 18, 2026, the Beacon Chain, which serves as the new consensus layer, began operating on the mainnet. This put in place a setup in which the existing PoA network and the new consensus layer run in parallel, achieving an important milestone toward The Merge.

With The Merge to be carried out this time, the existing block production method will be replaced by PoSA using the Beacon Chain, switching the network's consensus formation to the new mechanism.

As a result, JOC will, like Ethereum, have a configuration that separates the execution layer from the consensus layer, achieving a major evolution of its network foundation.

◽️ About the Tokyo Hard Fork

The Tokyo Hard Fork is an upgrade aimed at evolving Japan Open Chain into a next-generation network foundation, and mainly delivers the following two enhancements.

1. Improved Compatibility with Ethereum

By moving the consensus mechanism to a method nearly identical to Ethereum's PoS, JOC will come closer to Ethereum's standard specifications at the consensus layer, in addition to its existing EVM compatibility.

This makes it easier to leverage Ethereum's node software, operational tools, and technical expertise, and to follow future Ethereum protocol upgrades.

2. Strengthened Network Governance

Processes related to validator registration, management, and staking will be moved on-chain, improving the transparency and verifiability of network operations.

While maintaining a network operating structure run by trusted companies, this enables more transparent governance and validator operations based on economic incentives.

Following The Merge, the Tokyo Hard Fork is planned to be carried out in stages across four phases: Shapella, Dencun, and Pectra.

For details, please refer to the following press release.

https://www.jbfd.org/en/news/joc-tokyo-hardfork-testnet

◽️ For JOC Users

1. Temporary Network Usage Restrictions Accompanying The Merge

To ensure a safe migration, external access to both the old and new chains will be temporarily restricted for approximately 30 minutes before and after The Merge (approximately 1 hour in total). During this period, block production will continue, but transaction processing will be suspended.

The actual start and end times of the restrictions may vary depending on the network's progress. For details, please check the official countdown page.

Tokyo Hard Fork Countdown Page:

https://joc-website-preview.vercel.app/tokyo-hardfork/

2. Impact on General Users and Applications

With this hard fork, existing accounts, balances, smart contracts, transaction history, and the Chain ID will be maintained.

JOC holders, general users, and applications and services that use the RPC endpoints provided by JOC do not, in principle, need to take any additional action, apart from the temporary usage restrictions described above.

3. Request to Businesses Operating Their Own Nodes

Businesses that operate their own nodes must change their node configuration before The Merge. In addition to the existing Execution Client (Geth), you will need to set up a Consensus Client (such as Lighthouse).

If this applies to you, please review the following technical documentation and make the necessary preparations in advance.

Technical Documentation:

https://www.japanopenchain.org/docs/developer/connect-joc/mainnet/

◽️ Future Outlook

Starting with The Merge, the Company will carry out each phase of the Tokyo Hard Fork in stages, further strengthening compatibility with Ethereum, network performance, and governance.

Going forward, we will continue to build a secure and reliable blockchain infrastructure that supports the use of stablecoins and digital assets by financial institutions and business companies.

◽️ About "Japan Open Chain"

"Japan Open Chain" is a practical, Ethereum-compatible Layer 1 public blockchain co-operated by Japanese enterprises.

Japanese companies and web3 businesses participate in network operations as validators, providing a fast, low-cost blockchain infrastructure that anyone in the world can use.

It supports practical use cases such as stablecoins and digital assets, and aims to realize next-generation financial infrastructure.

Official Website: https://www.japanopenchain.org/en/

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Project Page: https://www.japanopenchain.org/en/

◽️ About Japan Blockchain Foundation Co., Ltd.

Japan Blockchain Foundation Co., Ltd. manages and operates the consortium for "Japan Open Chain," a public blockchain co-operated by Japanese companies.

By developing a network foundation that emphasizes governance and regulatory compliance, the company supports the social implementation of stablecoins and digital assets by financial institutions, enterprises, local governments, and others.

[ Company Overview ]

Company Name ：Japan Blockchain Foundation Co., Ltd.
Location ：Cerulean Tower 15F, 26-1 Sakuragaoka-cho, Shibuya-ku, Tokyo, Japan
Representative ：Representative, Daimei Inaba
Founded ：April, 2018
URL ：https://www.jbfd.org/en/
Business Overview ：Operation and Management of Web3 Infrastructure

◽️ For Inquiries Regarding This Press Release

We welcome interview and speaking engagement requests. Please feel free to reach out.

Japan Blockchain Foundation Co., Ltd. - Public Relations

Inquiry Form: https://www.japanopenchain.org/en/contact

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