World and Clock - A world clock that allows you to see the changing seasons

Abstract:

The world clock application "World and Clock - A World Clock that Sees the Changing Seasons" is inspired by the traditional Japanese clock "Washiki" from the Edo period. The dial scale will expand and contract according to the season and location. The iOS version of this application has been put on the App Store in China. The latest version 1.2 adds new functions such as list mode, map mode, and sunrise and sunset reminders. In addition, the Androidversion for regions outside mainland China has also been launched on Google Play on October 2, 2026 (Friday). The app is free and ad-free, with only optional in-app purchases to support development.

App Store (China):

https://apps.apple.com/cn/app/id6781682355

Google Play (outside mainland China):

https://play.google.com/store/apps/details?id=net.fsp.worldwadokei&hl=zh-CN

Official page:

https://www.infoarise.co.jp/app/worldwadokei/

A Japanese "moment" during the day, with different lengths in summer and winter, Tokyo and London

Japan's Edo period used a timekeeping method called "the irregular time method": daytime is from dawn to duskand night is from dusk to dawn of the next day. The day and night are then equally divided into sixtime periods, which are called "koku" in Japanese. For ease of understanding,it will be called "hour" below; but the "hour" here is not a fixed two hours,but a unit of time that changes with the season, latitude, and the length of day and night. Because the length of day and nightchanges with the seasons and latitude, the length of each hour also varies slightly from day to day. This application divides day and night based on the sunrise and sunset of the selected location, and divides them into six equal parts.

According to the calculations of this application, for example, in Tokyo, one hour of daylight before and after the summer solstice is about 2 hours and 30 minutes, and before and after the winter solstice is about 1 hour and 40 minutes; in London, which has a higher latitude, one hour of daylight before and after the summer solstice is about 2 hours and 45 minutes, and before and after the winter solstice is about 1 hour and 20 minutes.

"World and Clock" will draw a dial based on the sunrise and sunset times of the selected location, showingwhich time it is currently and how long an hour is locally. Through the design of the timepiece,you can feel the unique time rhythm of each place, which is different from the way modern clocks divide a day into hours of equal length.

※This application is not a faithful restoration of the structure or operation of historical Japanese timepieces.

Compare side by side or view the length of day and night in cities around the world on a map

Can display Tokyo, London, New York and other cities around the world, as well as user-added locations and timepieces.

・Detailed mode: Display a location and timepiece in a large size, slide left or right to switch locations

・List mode: Arrange up to 24 locations of small and timepieces in the form of cards

・Map mode: Arrange miniatures and timepieces on the map to see the length of day and night and the current time in each place

・Sunrise and sunset reminder (can be turned on in settings)

・Switching between 12-hour and 24-hour format

・Supports home screen widgets (supported by both iOS and Android versions)

Supports 6 languages: Japanese, English, Spanish, French, Simplified Chinese, and Traditional Chinese.

Message from the developer (FaSPel Hirohiko Fujikawa)

"People in the past lived in time that expanded and contracted with the four seasons. If we look at the 'momentsmoments' around the world side by side, we will find that even at the same moment, the time flowing in different places is very different. I hope everyone can enjoy these small discoveries."