Well, nengô (年号), the Japanese era names, are well known to every sword enthusiast. And most of you probably also know basically what they were about. But interesting for me was and is how fast the information of a newly proclaimed nengô made the rounds and arrived eventually in the forges of swordsmiths far away from the capital Kyôto. Fortunately there are minute records of when exactly each era was changed in Japanese history and but before I come to my actual examination I briefly want to introduce the practice of nengô, or gengô (元号) how they are also called. As so often, the Japanese nengô system has its origins in China where everything started with the Kengen era (建元, Chinese Jiànyuán ) in the year 140 BC when Emperor Wu of Han (漢武帝) ascended the throne. In Japan, the nengô system was adopted in the course of the Taika Reform in 645 but interrupted a decade later and once again re-adopted in 701 which became the first year of Taihô (大宝, 701). So far, so good. A nengô was basically connected to the ascension of a new emperor but was sometimes also changed due to other felicitous events or natural disasters. The emperor and his court officials now decided what motto the new era should have, picked the appropriate characters, and picked on which day it should come into effect. That means in earlier years, the change in nengô took not automatically place when a new emperor ascended the throne. So the first year of the new nengô (gannen, 元年) continues until the next lunar new year, which is understood to be the start of the nengô´s second year. To give an example: The Bunmei era (文明) came into effect on the 28th day of the fourth month Ônin three (応仁, 1469). Thus 1469 was both Ônin three and Bunmei one. And the other way round, the first year of Bunmei lacks accordingly a first, second and third month as these months lied in the previous Ônin era.
Bureaucracy had always been elaborate in Japan and so the news of the death of an emperor and the proclamation of the start of a new nengô – sometimes even up to two years after the ascension of the next emperor – reached the most distant provinces surely within weeks, or in some cases maybe months. And signatures on swords are also a good way to proof the speed of an era change. To do so, we have to focus of course on the first year of a nengô, the gannen. But also we have to be careful about the custom to date swords by default with the second and eighth month regardless in what month they have actually been made. This „second month eighth month thing“ is said to go back to the auspicious change in season, i.e. from winter to spring in the case of the second month and from summer to fall in the eighth month. At the same time it is said that the water and the air are especially apt for the sword forging process in these months. Others assume that as both the characters for the numbers „two“ (二) and „eight“ (八) have quasi two halves and that these halves allude to the sharpness of a sword which cuts things in half. However, it is interesting to note that the custom of using the second and eighth month regardless of when the sword was forged started about with the Kanshô era (寛正, 1460-1466). That means a trend towards these two months can not be confirmed in Kamakura and Nanbokuchô era date signatures. In short, pre-Ôei (応永, 1394-1428) date signatures show about equally all twelve months.
A good example for the speed the change in nengô made the rounds is a tantô of Osafune Norimitsu (則光) which is dated „Ônin gannen sangatsu-hi“ (応仁元年三月日, „a day in the third month Ôei one “). According to transmission, the Ônin era was proclaimed by emperor Go-Tsuchimikado (後土御門天皇, 1442-1500) and his court because of repeated severe calamities, namely to come into effect on the fifth day of the third month of the second year of the previous Bunshô era (文正). So as the tantô of Norimitsu is dated with the third month, we learn that the information of the era changed had reached Bizen in the very same month. To remember, Osafune is about 170 km from Kyôto. But the same works also for the way north. For example there exists a katana of Uda Kunimune (宇多国宗) which is dated with the 16th day of the eighth month Chôkyô one (長享, 1487). The Chôkyô era was proclaimed by the same emperor Go-Tsuchimikado for the 20th day of the seventh month Bunmei 19 (文明, 1487) because of the ongoing turmoils initiated by the Ônin War and an epidemic. So Kunimune knew about the change in nengô at the latest after 27 days after it started. His production site was about 250 km from Kyôto. Another example for blades of a smiths around the border between two nengô. There are a katana and a tantô extant by Osafune Sukesada (祐定) of which the katana is dated with the second month Bunki four (文亀, 1504) and the tantô with the second month Eishô one (永正, 1504). The Bunki era was changed by emperor Go-Kashiwabara (後柏原天皇, 1464-1526) to the Eishô era on the 30th day of the second month of its fourth year because the sexagenary circle changed. The latter was namely also a reason to change a nengô because the year it happened was considered as inauspicious. Quasi better have a new era name to counteract the inauspicious cosmological signs. It was namely belieced that one could, in fact, change fortune by changing the motto of an era. Anyway, the two blades show that the katana was made right before, and the tantô right after the change of the nengô.
But sometimes the smiths missed a change in nengô. For example there exists a wakizashi by Osafune Katsumitsu (勝光) which is dated with a day in the sixth month Meiô ten (明応, 1501). But the Meiô era had already been changed by the aforementioned emperor Go-Kashiwabara on the 29th day of the its second month to Bunki (文亀). So Katsumitsu was four months behind with his date signature in question. Of course we also know even „worse“ examples like a wakizashi by Osafune Yukimitsu (幸光) dated with the 15th day of the second month Eiroku 16 (永禄, 1573). But Eiroku had changed to Genki (元亀) about three years before, i.e. in Eiroku 13 (1570). Rare on swords but still existing are the so-called „shi-nengô“ (私年号), unofficial era names popping out here and there throughout Japanese history. They were used locally and by certain institutions like temples and shrines and represent a denial of the ear name established by the emperor, thus they concentrate in periods of political and social unrest. In many cases, just a certain shi-nengô year appears in a text and so we don´t know of most of them how long they actually lasted. One such shi-nengô can be found in a 32-plate suji-kabuto helmet bowl of Myôchin Nobuie (明珍信家) depicted in Matsumiya Kanzan´s (松宮観山, 1686-1780) „Meikô-zukan – zokushû“ (名甲図鑑続集). It is described in the latter publication as bearing the date Hôju ninen kinue-uma shôgatsu-hi“ (宝寿二年甲午正月日, „a day in the first month of the second year Hôju, year of the horse“). The Hôju era seems to have been in use in and around Kai province. It lasted two years and Hôju two was equivalent to Tenbun three (天文, 1534). I wasn´t able to find an oshigata with a shi-nengô on a sword blade yet but I would be very pleased if somebody could provide me with one.