GMO Aozora Net Bank suspended its banking API twice after detecting unauthorized external communications, interrupting Japanese-yen payment routes used by Binance Japan and BitTrade. The Japanese bank’s two precautionary shutdowns, spanning the evening of November 10 and early November 11, amounted to seven hours and 11 minutes of combined downtime.
Both cryptocurrency exchanges announced the restoration of yen deposits and withdrawals after the first interruption. That was before the bank shut the API again at 1:02 a.m. Japan time on November 11. GMO Aozora confirmed a second restoration at 6:25 a.m., but separate, post-restart notices from Binance Japan and BitTrade were not identified in the public announcements reviewed.
The bank has repeatedly said it found no leakage of personal information or unauthorized outflows of funds. It has not identified who generated the suspicious traffic or described a confirmed breach of account balances. The documented event is a protective shutdown of part of its API connectivity infrastructure, not a reported theft from the bank or the exchanges.
Two security-related API suspensions lasted over seven hours
GMO Aozora said it detected unauthorized communications targeting part of its bank API connection platform around 8:30 p.m. Japan Standard Time (JST) on November 10. It suspended the service at 8:42 p.m. and restarted it at 10:30 p.m. after the unusual traffic had stopped. That first window lasted one hour and 48 minutes.
The traffic appeared again. The bank suspended its API for a second time at 1:02 a.m. on November 11, then resumed service at 6:25 a.m. after confirming it was safe to do so. The second interruption lasted five hours and 23 minutes. Together the two windows total seven hours and 11 minutes; they were not one uninterrupted outage.
Both stoppages took place on November 10 in Cairo time, from 1:42 p.m. to 3:30 p.m., then from 6:02 p.m. to 11:25 p.m. Japan’s published dates remain November 10 and 11. The bank also warned that further precautionary interruptions could be necessary while it continued monitoring.
The bank’s public statement does not say whether the activity was an attempted denial-of-service attack, a credential intrusion or another type of unauthorized request. Nor does an API shutdown establish that ordinary deposit accounts or the bank’s entire online service were unavailable.
Binance Japan and BitTrade restored yen routes before second halt
Binance Japan said the bank notified it about the incident around 8:30 p.m. JST. Deposits and withdrawals of Japanese yen through GMO Aozora became unavailable, while PayPay Money and Docomo SMTB Net Bank routes remained operational. Binance subsequently announced that the affected route had reopened and that transactions initiated during the pause would be reflected progressively.
BitTrade reported a narrower breakdown by payment method: bank-transfer yen deposits and yen withdrawals were interrupted, but quick deposits, convenience-store deposits and Pay-easy deposits remained available. The exchange timestamped its initial restoration at 10:56 p.m. JST on November 10 and said pending transactions would be processed in sequence.
Those restoration announcements predate the bank’s second shutdown. There was a way around the first interruption for some users, but not through the affected bank route. Neither exchange provided a verified final count or value of delayed yen transfers, and the published notices did not establish whether the second bank halt led to a renewed customer-facing suspension or when every pending transfer was cleared.
The episode follows a seperate GMO Aozora payment-route problem at Binance Japan on November 1–2. That earlier disruption delayed yen deposits and withdrawals until November 2; its cause was not linked by the exchange or bank to the unauthorized API communications disclosed on November 10. The dates and shared provider alone do not prove a common technical fault.
Bank API risks differ from crypto withdrawal outages
This incident concerns the banking infrastructure used to move yen into and out of exchange accounts, not the blockchains used for cryptocurrency deposits or withdrawals. That distinction is especially relevent for BitTrade, which had only recently restored crypto withdrawals after a 48-hour failure at an external AML screening provider. The November 5–7 interruption affected cryptocurrency verification; the latest restrictions involved fiat banking APIs. No common supplier or cause has been established.
External bank dependancy has affected Japanese trading firms before. On November 2, OANDA’s Japanese brokerage reported delayed withdrawals after a different partner, Docomo SMTB Net Bank, experienced problems processing bulk payments. DaveFinances documented the affected withdrawal window and resubmission plans. That incident does not implicate GMO Aozora, but it provides a concrete example of payment instructions being delayed outside a trading firm’s own systems.
Japan’s Financial Services Agency addresses system interruptions in its bank supervisory guidelines, which describe incident reporting, recovery planning, customer communication and investigation of causes. The guidelines do not establish a violation by GMO Aozora in this case, nor has a regulatory enforcement action been announced in connection with the episode.
The first restart did not hold, and that is part of this story. What remains to be disclosed is the origin of the repeated traffic, the precise API functions affected and whether the exchanges had to reprocess further transfers after the second shutdown. GMO Aozora’s 6:25 a.m. restoration confirms the bank service was back; it does not by itself confirm that every exchange customer had already recieved a delayed yen credit or withdrawal.
Johan Shamshad is Editor-in-Chief at Dave Finances, covering financial markets, digital assets, trading platforms, brokers, fintech, payments and regulation. Since 2023, he has also worked as an editor at Gulf News, the UAE English-language newspaper published by Al Nisr Publishing LLC. His work focuses on market-moving developments, company disclosures, regulatory changes and trading infrastructure, with an emphasis on primary-source verification and practical context for traders and investors.