National Treasures & Important Cultural Properties
of National Institutes for Cultural Heritage, Japan

This is a seal of an army corps stationed in Mikasa, Dazaifu (currently, Dazaifu city and its surrounding area) that was called To-no-Mikado. The seal surface is square, on which four letters of "Mikasadan In" are carved in relief in two lines with two letters each. The seal has a plectrum-shaped knob without a hole. This was accidentally found by a farmer in a mulberry field in 1927. In 1899, another copper seal of almost the same shape and size, on which "Ongadan In" was carved, was excavated from the premises of Mizuki Elementary School in Dazaifu City.
Under the legal codes of the Nara period called Ritsuryo, army corps were stationed at various places across the nation and there were four army corps in Chikuzen (currently, the northwestern part of Fukuoka). Although the defense codes stipulate that when a big army corps is required, no less than 1000 soldiers should be stationed, the actual size of each corps is unknown. The military system was reformed in 739 and 780. By 792, most of the army corps stationed across the nation were discontinued, but those stationed in Dazaifu, such as Mikasa and Onga, which are important sites in terms of national defense, were maintained.