About Koyomi Days

What Koyomi Days is

Koyomi Days is a free set of tools for the I Ching and East Asian calendar notes. All 64 hexagrams sit on a single rule: slide to any of them, or cast one with three coins or the current hour, and read the classic text alongside.

No sign-up. It works the same on phone and desktop.

Worked out precisely

Solar terms come from VSOP87 astronomy, the time method follows the plum-blossom rule, and the line texts are checked against the received Chinese text. The same input always gives the same result, and every cast shows how it was worked out.