Zengin is Japan's domestic inter-bank settlement system, operated by the Japanese Banks' Payment Clearing Network. The format is a fixed-width text record set with a Japanese-specific JIS character encoding. The rail handles roughly 1.6B transactions / year.
The Zengin migration to ISO 20022 (Zengin-EDI II) is in progress with a target of late 2027 for full pacs.008 / pacs.002 adoption. Today, customer-bank integration is JIS-text-record format submission via dedicated corporate-banking channels.
iso-compliant treats Japan / Zengin as Phase-3 scope. The interesting integration challenge is the JIS-to-Unicode round-trip — Japanese corporate names contain characters outside ASCII, and the SWIFT CBPR+ "Latin only" rule does not apply domestically.