In 604, along with the promulgation of the Seventeen Article Constitution, Prince Shotoku established the court ranks, kan’i junikai or the twelve grades of cap rank (or twelve grades of colored coronets). Under this system, the imperial court relied on experienced and skilled officials who were appointed and promoted on the basis of their ability to perform specialized administrative tasks.
Courtier's colours and cap ranks (Left to right: toku; jin; rei; shin; gi; chi
The ministers, officials of the highest status under the system, were given caps of purple silk decorated with gold and silver indicating their assigned court rank. The silk was colored by purple dyes from the “murasakigusa” (Lithosperumum erythorhizon siebetzucc) a plant which is today a protected species. Murasaki or purple has since ancient times been a color that symbolized authority, nobility and splendor.
Below these ministers, the other officials of twelve grades wore caps of different colors, other than purple.
One high managerial official post emerged; that of the imperial secretary (maetsukimi/taifu) who presided at important court events, the reception of foreign missions and imperial conferences attended by high-ranking ministers. The imperial secretary reported directly to the throne.
At lower levels, other officials bearing the cap and ranks were chosen for their ability to perform specialized functions: the use of imported techniques for producing weapons and tools, building palaces and temples, making statues, bells, paintings and other symbolic and ecorative works of art. These newly created ranks and positions were a significant immigration policy that made provision for immigrants with expertise and achievement — as opposed to a rank by birth in a historically prominent local clan.
Origin of cap-and-court rank system
This cap-and-court rank system that hailed originally from China, was not identical to those in place in the Paekche and Koguryo Korean kingdoms, and so is thought to have been a modified creation of Prince Shotoku. For the time being, the old hereditary clan title uji-kabane system remained in place but the kan’i junikai system set in motion the first step towards the replacing of the old uji-kabane order.
Heritage of Japan 