About Kurashi Tools

What we make

Kurashi Tools provides small utilities for date labels, ages and other information that is easy to misread on Japanese paperwork. The English section is written for foreign residents, international students, parents and workers who need a clear result without creating an account.

How the tools operate

Calculations run in your browser. The service does not require a runtime account database or send the dates you enter to a calculation server. Explanations show the assumptions and boundaries that matter, including Japanese era transition dates.

Sources and checks you can inspect

We use the Cabinet Office for recent era changes, National Archives proclamations for Taisho and Showa, the National Diet Library for calendar history, MEXT for school-age boundaries, and the National Astronomical Observatory for the stem-branch cycle. Each English tool links the relevant source and explains what it supports. Japanese-only references are labelled; our English wording is not an official translation.

Fixed examples are compared with the same conversion, age and zodiac functions used by the tools. Checks include both sides of era transitions, birthday boundaries and month-end handling. Representative mobile and desktop pages are also reviewed. These checks cover the stated cases, not every institution, device or historical calendar.

Try a checked era example

Corrections and review dates

A page update records an actual content change. A source-check date records when the linked material was reviewed, not an automatic daily certification. If a source changes or an error can be reproduced, we review the affected explanation and calculation together. Substantial corrections are recorded in our operating notes and relevant update notices.

To report a problem, send the page URL, a fictional input, and the expected and actual output. Do not send a real birth record or identity document. The Japanese and English tools share calculation functions; their language does not change the result or remove the limitations explained on the page.

Accuracy and responsibility

Results are intended as practical reference material. Government offices, schools, employers and other organizations may apply their own forms and cutoff rules. Always follow the issuer's current instructions and compare important dates with original records.

Part of GreedMonster

GreedMonster's shared operating information introduces the brand and its services. Kurashi Tools keeps its calculation sources, verification limits, privacy information and correction guidance here. The hub does not replace these service-specific explanations.