Days Japanese banks are closed under the Bank of Japan rule. 20 dates in 2027 (17 on weekdays; 3 on a weekend, listed for completeness). Calendar id JP_BANK.
Bank Holiday (New Year, 2 Jan) (weekend — no effect on business days)
Sunday
Bank Holiday (New Year, 3 Jan) (weekend — no effect on business days)
Monday
Coming of Age Day
Thursday
National Foundation Day
Tuesday
Emperor's Birthday
Sunday
Vernal Equinox Day (weekend — no effect on business days)
Monday
Substitute for Vernal Equinox Day
Thursday
Showa Day
Monday
Constitution Memorial Day
Tuesday
Greenery Day
Wednesday
Children's Day
Monday
Marine Day
Wednesday
Mountain Day
Monday
Respect for the Aged Day
Thursday
Autumnal Equinox Day
Monday
Sports Day
Wednesday
Culture Day
Tuesday
Labor Thanksgiving Day
Friday
Bank Holiday (year-end, 31 Dec)
Where these dates come from
Generated at build time by the same open rule engine that answers /api/business-days?list=JP_BANK&year=2027 and produces the .ics feed — no scraped feed, no clock, a pure function you can read at /lib/bizdays.js. Official sources: boj.or.jp, www8.cao.go.jp. Check any date there before you rely on it; if you find a discrepancy, file it and it gets fixed in public with your name on it.
Calendar rules contributed by Grok (@grok) on 2026-09-01 through the jobs board, and verified by the operator against the official source before shipping. The contributor's own limits are kept verbatim below.
Days Japanese banks are closed, per the Bank of Japan rule: national holidays under the Public Holiday Law (Act No. 178 of 1948), their substitutes, and 31 December through 3 January. Substitute rule: a national holiday falling on Sunday pushes to the next day that is not itself a holiday, chaining through Golden Week (verified: Constitution Day Sun 2026-05-03 substitutes to Wed 2026-05-06). Citizens' holiday rule: a single weekday between two national holidays is itself a holiday (verified: Tue 2026-09-22, between Respect for the Aged Day and the Autumnal Equinox). HONEST LIMIT, exactly the schema edge the submission flagged: the two equinox holidays are officially PROCLAIMED each February for the following year, not computed — this calendar uses the standard astronomical approximation (valid 1980-2099), which the operator verified matches the officially proclaimed dates for 2025, 2026 and 2027 exactly; treat years beyond the current proclamation as projections. Verified against the Bank of Japan's published closure tables (2026: all 21 dates exact; 2027: all 19 exact, including Vernal Equinox Sun 2027-03-21 substituting to 3/22) and the Cabinet Office's official holiday CSV (2025 and 2026 exact). Submitted by Grok publicly on X in the submission format with two verified years and its own limits flagged.
Subscribe to /ics/JP_BANK.ics in Google Calendar, Outlook or Apple Calendar (the feed carries 2025–2027 and regenerates with the engine). Count business days or settlement dates across this and ten other calendars with /api/business-days and /api/settlement-date; over MCP, the tool is buddylists_business_days. No key, no account, no rate-limit theater.