Yen Stablecoin JPYC Spikes to 4.14 Yen in Debut on Upbit

First Yen Stablecoin on a Korean Exchange

The Japanese yen stablecoin JPYC spiked more than threefold within minutes of its debut on South Korea's largest crypto exchange, Upbit, on September 17 — the first time a Korean trading venue has ever listed a yen-pegged token. Trading opened at 18:00 KST across the Korean won, Bitcoin (BTC) and Tether (USDT) markets, with the first print at 12 won, or roughly 1.32 yen. Buying then accelerated sharply: the KRW pair touched 37.60 won, about 4.14 yen — roughly 3.1 times the opening price and far above the 1 yen a JPYC token is redeemable for. Because prices on an order-book exchange form from user-to-user trades rather than the issuer's own desk, a newly listed stablecoin does not automatically trade at its redemption value. The dislocation spilled onto other venues within the hour, setting up one of the year's more unusual arbitrage windows.

Arbitrage From Both Sides

That window ran in two directions at once. JPYC Inc.'s own platform, JPYC EX, lets verified users mint or redeem each token for exactly 1 yen, with backing that includes yen deposits and Japanese government bonds. As Upbit's price ran toward 2 and 3 yen, Korean buyers chased cheaper tokens on decentralized exchanges while Japanese holders minted at par and sold into the premium. On DeFi venues such as Uniswap, the Ethereum pair reached about 3.11 yen and the Polygon pair about 2.71 yen as of 19:30 JST, with one thinly traded Polygon market printing a 15-minute high near 6.07 yen at 19:15. On-chain data shows circulating supply swelled to roughly 4.26 billion JPYC by 09:00 JST on September 18 — about 2.2 times the prior day. Deposits, sent from a user's crypto wallet, had opened on Ethereum only at listing; Polygon and Kaia deposit support went live at 18:44 the same day.

Issuer Halts Minting Overnight

The surge quickly stressed the issuer. JPYC Inc. suspended issuance reservations on Ethereum at 20:34 JST and on Polygon at 22:19, restoring both — Ethereum at 23:43 and Polygon by 00:22 on September 18 — while the cause remained under investigation; the company has not confirmed any link between the halt and the supply spike or the price swings. Upbit, for its part, published a trading notice warning that Korean users face eligibility constraints when redeeming directly through JPYC EX at 1 yen, and that a stablecoin's market price can diverge from the value of the asset it tracks. JPYC CEO Noritaka Okabe pushed back on X against the idea that a listing itself creates value, suggesting — expressly as speculation — that automated trading bots or early-liquidity hunters were behind the spike. By 02:25 JST the token had fallen back to about 1.02 yen on aggregate trackers.

Okabe: Inventory Ran Short

In comments on September 18, Okabe gave a more operational account of the episode. Issuance demand ran so hot that the company ran short of inventory overnight, and a jump in account applications pushed staff into irregular late shifts, he said. He had not known the Upbit listing was coming: first-day turnover exceeded 30 billion yen, a figure he described as far beyond his expectations. He also flagged a regulatory asymmetry — overseas exchanges are not subject to Japan's 1 million yen cap on issuance and redemption, which he argued gives JPYC a faster path abroad — while noting that no domestically licensed electronic payment instruments dealer has begun trading the token yet; SBI VC Trade received the first such registration in March 2025 and Coincheck completed the second in August 2026. Traders who bought the top, however, were left holding losses as the price reverted toward par. Readers tracking the market in real time can follow live spot and futures prices on Bitget.

Arbitrage Held the Peg

Taken together, the threads describe a single mechanism: a stablecoin's peg is not a property of the token itself but of the arbitrage connecting fragmented markets to the issuer's redemption desk. The most load-bearing records here are primary — on-chain supply data showing roughly 4.26 billion JPYC in circulation by 09:00 JST on September 18, paired with the issuer's standing 1:1 mint-and-redeem guarantee — the two facts that let arbitrageurs collapse a near-4-yen price back to par within hours. COINOTAG's read: as long as redemption access stays jurisdictionally uneven, every new listing on a fresh market will invite the same dislocation, and the edge will belong to whoever can move supply across chains fastest.