Koden, rice fields granted by the state (功田)
The existing Yoro Ritsuryo Code stipulated in its provisions of Denryo (rice field law) Article 5, Article of Koden, that those who did meritorious deeds would be divided into four classes of Daiko, Joko, Chuko, and Geko according to the degree of their achievements from top to bottom, and that Daiko would be granted inheritance of their Koden generation to generation forever, Joko for three generations (down to great-grandchildren), Chuko for two generations (down to grandchildren), and Geko only to their children. In the same article, it was also stipulated that Koden would never be confiscated unless, for Daiko, they rebelled against the government, and for those other than Daiko, they committed any of eight unpardonable crimes.
Under the kochi komin system, basically rice fields were to be withdrawn by the government (i.e., rice fields were returned to the state) when the person who had been granted the fields died; therefore, it was exceptional that the rice fields were allowed to be inherited for generations. In particular, getting Daiko class (granting of permanent inheritence of rice fields) was an exceptional case and only four persons have been recognized as Daiko in history: FUJIWARA no Kamatari (645), EMI no Oshikatsu (758), TAIRA no Kiyomori (1167), and MINAMOTO no Yoritomo (1190), each person being granted 991,740 square meters of land (Koden was confiscated from Oshikatsu and Kiyomori for the reason that they or their descendants had rebelled against the government).
As stipulated in the law, originally Koden was treated as Yusoden (rice fields subject to taxation) like Kubunden (rice fields given to each farmer under the Ritsuryo system), but later, after the Heian period, Koden tended to be treated as Fuyusoden (tax free rice fields). It is considered that actual farming of Koden was done by tenant farmers in the neighbor.
Examples of conferment of Koden
The article in the entry of the ninth day of the twelfth month of the first year of the Tenpyohoji era (757) in Shoku Nihongi shows how Koden were provided. Details are shown below. The areas of Koden are parenthesized.
For the distinguished service in the Isshi incident
FUJIWARA no Kamatari (991,740 square meters)
SAEKI no Komaro (402,630 square meters)
For the distinguished service in the rebellion by FURUHITO no Oe no Miko
KASA no Shidaru (198,340 square meters)
For the distinguished service in the Jinshin War
OWARI no Osumi (396,680 square meters)
For the great achievements of compilation of Taiho Ritsuryo Code
For the distinguished services in the TACHIBANA no Naramaro rebellion
KAMITSUMICHI no Hitatsu (198,340 square meters)
For the great achievements as the Japanese envoy to Tang Dynasty China
SAKAIBE no Iwashiki (59,502 square meters)
For the great achievements of compilation of Yoro Ritsuryo Code
YAMATO no Nagaoka and YAKO no Mami (39,668 square meters for each), YATSUME no Mushimaro and SHIOYA no Kichimaro (49,585 square meters for each), and KUDARA no Hitonari (39,668 square meters)
In addition to them, it is recorded that Koden was granted for the great achievements to EMI no Oshikatsu (FUJIWARA no Nakamaro) who assumed the real political power during the middle of the Nara period, WAKE no Kiyomaro who prevented Dokyo from acceding to the throne, FUJIWARA no Hidesato who defeated TAIRA no Masakado, TAIRA no Kiyomori who established the Taira clan government, MINAMOTO no Yoritomo who defeated the Taira clan government and established the Kamakura bakufu, and others.