A long time ago, in the age of paper, in order to efficiently utilize limited resources, there existed “perpetual calendars,” which arranged calendar information for days of the week in chart form to correspond with any month and date, making them usable in perpetuity.
While such calendars are for the most part unnecessary in the modern age, what if we could make such a thing into an app?

Of all times and places, this is likely the most simple of perpetual calendars. Information has been compactly organized into manageably memorizable sizes, allowing you to compute the days of the week with the simplicity of making case classification or addition calculations on paper. The thing we want to emphasize however, is that it’s not the app doing the calculations, but you, yourself. Using a tiny chart, and tiny calculations. Eventually, perhaps you will be able to “graduate” from this app, and become able to calculate the days of the week through mental arithmetic.

By nature, this is an app that’s short in practicality. But why not forget the burdens of this transient world once in a while, and have some fun with this calendar?

Recommended if you:
- have an interest in calendars.
- want to exercise your brain.
- would like to surprise your friends with some special skills.

For more detailed usage instructions:
More detailed usage instructions for this app are available at Info(the button circling the “i”). Information on variables and symbols used in the app are included here as well, (although the word count is large) so please read beforehand.

About in-app purchases:
- Tutorial
This will unlock the tutorial function. The tutorial will allow the user to input a date and learn how to use the app using that date.

What's New

Version 1.0

This update is signed with Apple’s latest signing certificate. No new features are included.


Kentaro Suzuki
11.4 MB
Requires iOS 8.4 or later. Compatible with iPhone, iPad, and iPod touch.
English, Japanese
Age Rating
Rated 4+
© 2015 Kentaro Suzuki.


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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