Quantum Solutions (Tokyo Stock Exchange: 2338) is Japan's largest listed Ether treasury company and the world's second-largest ETH digital asset treasury outside the US, holding approximately 5,968.56 ETH and 5.07 BTC as of Q4 of its fiscal year ending February 2026, backed in part by ARK Invest and a 26bn yen (USD 180m) funding round completed September 2025, with a stated long-term target of 100,000 ETH. On 25 November 2025, Quantum Solutions and HashKey Cloud announced Japan's first DAT (digital asset treasury) staking partnership, using HashKey's CaaS (custody-as-a-service) platform, making it the first Japanese listed company to stake its treasury holdings rather than simply accumulate and hold.
What it is
Quantum Solutions runs an ETH-accumulation strategy on the same general Japanese legal and accounting machinery Metaplanet uses for Bitcoin (J-GAAP fair-value treatment under PITF No. 38), but distinguishes itself through the HashKey Cloud staking partnership: the company's ETH holdings are staked through HashKey's institutional infrastructure rather than held passively, with the partnership also exploring restaking and DeFi yield aggregation.
Relevance to tokenisation
Quantum Solutions is the worked example of the governance question a staking-enabled corporate treasury raises that a pure-accumulation DAT does not: a board choosing to stake is making a validator-selection and custody-delegation decision, not just a balance-sheet allocation decision, and Japan's disclosure regime for listed crypto-holders has not yet been tested against staking-specific risk disclosure. See Reading a Japanese listed digital-asset treasury company for the fuller comparison.
Related
- Reading a Japanese listed digital-asset treasury company.
- Japan for the jurisdiction-level regulatory posture.
- Metaplanet for the BTC-side comparison.
- HashKey Group for the staking infrastructure provider.