暦注カレンダー is an education and reference application designed for iPhone users who wish to explore various traditional Japanese calendars. This free app supports a wide array of calendar annotations, including holidays, lunar calendars, and various astrological elements such as the six days of the week and the twelve branches of the zodiac. Additionally, users can find detailed information on the twenty-four solar terms and other significant dates, making it a valuable resource for anyone interested in Japanese cultural practices.

One of the standout features of 暦注カレンダー is the 'Lucky Day Calendar' which highlights auspicious dates, including rare occurrences when two lucky days coincide. The app offers customization options, allowing users to toggle the visibility of specific calendar annotations and modify text and background colors for better readability. This flexibility ensures that users can tailor the app to their specific needs, enhancing the overall user experience.