DATE INSCRIPTIONS - ZODIACAL
1930 - 1945

During the World War II period, some swords were dated using the archaic cyclical zodiacal system. This system involves a 60 year repeating cycle. Below are the Kanji with their translation and the equivalent date for the years 1930 to 1945, the time period when this method was most used. It was used almost exclusively on swords bearing the Koa Isshin mantetsu and mantetsu signatures. This dating method may also be found on other swords of the period.

The first Kanji in the date inscription of Koa Isshin and mantetsu blades will be (Showa), the name of the nengo (era) beginning in 1926, followed by the zodiacal year. The last Kanji in the date inscription of mantetsu blades is normally (haru), meaning "spring" - the most auspicious time for forging swords. Thus, the date inscription below reads "Showa Mizunoto Hitsuji Haru" or spring of 1943.

          

On some nagako another archaic dating is used; dating from the founding of the Japanese empire with the first Emperor Jimmu. The reign of Jimmu is taken to be from 660-585 BCE. Dates using this system will begin with the Kanji at the right followed by Kanji reading 26xx (2600).Therefore to obtain the date in the modern calendar, simply subtract 660 from the date on the nakago. Example: if the nakago reads 2603 from the founding of the empire, the modern date would be: 2603 - 660 or 1943 CE.