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Japan Traditional Calendar (Koyomi) API
x402
Japan Traditional Calendar (Koyomi) API is a paid API for AI agents from japan-business-day-api.matchan962.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-12).
Returns full Japanese traditional calendar data for a given date, including rokuyo lucky-day rating, Japanese era date, lunisolar calendar date, 24 solar terms, and year eto.
Price / call$0.005
Success—
StatusUnknown
How this service works
Japanese traditional calendar for a date: rokuyo (taian/butsumetsu... lucky days used for weddings, funerals, contracts), Japanese era (Reiwa) date, old lunisolar calendar date incl. leap months, 24 solar terms (sekki) and year eto. Verified against the National Astronomical Observatory of Japan.
Output
Returns a structured object for the queried date containing: the rokuyo category (e.g. taian, butsumetsu, sensho, tomobiki, shakku, senbu), the Japanese era name and year (e.g. Reiwa 7), the lunisolar calendar month and day including leap month status, the applicable 24 solar term (sekki) if any, and the year eto (heavenly stem and earthly branch zodiac designation).
Example use cases
Wedding date auspiciousness check
“We're planning a Japanese wedding and want to check if October 18, 2025 is a taian day — can you look up the rokuyo and full koyomi details for that date?”
Business contract signing timing
“My Japanese business partner wants to sign the deal on a lucky day — can you check the rokuyo for November 3, 2025 so we know whether it's taian or one of the unlucky days like butsumetsu?”
Traditional calendar conversion for cultural content
“I'm writing about Japanese seasonal culture — what are the traditional calendar details for the winter solstice, December 22, 2025? I'd love the sekki solar term, the eto, and the lunisolar date.”
Technical details
Endpoint
GEThttps://japan-business-day-api.matchan962.workers.dev/v1/koyomi?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need authoritative traditional Japanese calendar data for a specific date, particularly rokuyo for ceremony/event planning (weddings, funerals, contract signings), era-based date display for Japanese audiences, lunisolar date conversion, or seasonal solar term annotation. Prefer this over generic calendar APIs when Japanese cultural accuracy is required and results are verified against the National Astronomical Observatory of Japan.
Side effects
- Missing or malformed 'date' query parameter returns a 400 error
- Dates outside the supported historical or future range may return empty or error responses
- Network timeout on the Cloudflare Worker edge function
- Dates before the Meiji era or far future dates may have limited era/rokuyo accuracy
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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