江戸の刻 (Edo no Koku) Is Now Available for iOS
March 2, 2026 — STROBOFACTORY
The iOS app 江戸の刻（えどのこく） is now available on the App Store, letting you experience the variable-hour timekeeping system used in Edo-period Japan in real time.
What Is Variable-Hour Timekeeping?
This solar-based system divides the time from sunrise to sunset into six daytime periods and the time from sunset to sunrise into six nighttime periods. The length of each period changes with the seasons: daytime periods are longer in summer, while nighttime periods are longer in winter. The system was widely used in Japan until the switch to Western fixed-hour timekeeping in 1872, the fifth year of the Meiji era.
Key Features
| GPS Support | Automatically calculates variable hours accurately using sunrise and sunset times at your current location |
| Twelve Zodiac Signs | Displays the twelve periods represented by the zodiac signs: Rabbit, Dragon, Snake, Horse, Sheep, Monkey, Rooster, Dog, Boar, Rat, Ox, and Tiger |
| Bell Counts | Animated displays show the historical bell counts used in the Edo period, from nine strikes down to four |
| Automatic Day and Night Modes | The screen's color scheme changes automatically between day and night, accompanied by animations of the sun and moon moving across the sky |
| Bell Notifications | A bell sounds when each period changes, helping you experience the rhythm of daily life in Edo-period Japan |
| Time Preview | Use a slider to preview changes throughout the day, with quick buttons for sunrise, noon, sunset, and midnight |
The Idea Behind the App
Wake with the rising sun and sleep when the sun sets and darkness falls.
Reset the disrupted circadian rhythms of modern life.
For those of us accustomed to uniform modern hours, a system in which each period changes length with the seasons offers a fresh perspective. Experience on your smartphone how people in the Edo period understood time and lived in step with the sun.
App Information
| App Name | 江戸の刻（えどのこく） |
| Price | ¥300 (one-time purchase) |
| Supported Devices | iPhone / iPad (iOS 16 or later) |
| Category | Utilities |
| Developer | STROBOFACTORY |
This app uses location information (GPS) to calculate sunrise and sunset times. Location data is processed only on your device and is never sent externally.