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Western → Japanese
Japanese → Western
Holidays
API

calendar_month Western → Japanese
history_edu Japanese → Western
event Holidays
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Dashboard › How to use the API › OpenAPI Reference

API

API documentation

OpenAPI reference for the Seireki JSON API.

description OpenAPI YAML

Gengō-kun

A simple, accurate Western↔Japanese era converter and Japanese public holiday lookup.

© 2026 Genkō-kun

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calendar_month Western → Japanese
history_edu Japanese → Western
event Holidays