Calendar reform the traditional fixed arithmetic Hebrew calendar, respectively. Calendar proposals that introduce a thirteenth month or change the Julian-Gregorian system of months often also propose new names for these months. New names have also been proposed for days out of the week cycle (e.g., 365th and leap) and weeks out of the month cycle. Proposals to change the traditional month and weekday names are less frequent. The Gregorian calendar obtains its names mostly from gods of historical religions (e.g., Thursday from Nordic Thor or March from Roman Mars) or leaders of vanished empires (July and August from the first Cæsars), or
Adoption of the Gregorian calendar Japan decided to officially replace its traditional lunisolar calendar with the Gregorian calendar in 1872, so the day following the second day of the twelfth month of the fifth year of the Meiji emperor's rule, became . (The Japanese rendering of the Western months is simply "ichi-gatsu" or "One-month" for January, "ni-gatsu" or "Two-month" for February, etc.) This brought Japan's calendar in alignment with that of the major Western powers (excluding Russia). To this day, however, it is common to use Nengo, reign names instead of the Common Era or Anno Domini system, especially for official documents; for instance, "Meiji"