Rensho

The rensho, literally “co-signatory”, was the assistant to the shikken (regent) of the Kamakura shogunate in Japan. The rensho placed his signature next to that of the shikken on official orders. In 1224 the third shikken Hōjō Yasutoki appointed Hōjō Tokifusa as the first rensho. From then on, the rensho was chosen from influential members...
Found on http://en.wikipedia.org/wiki/Rensho
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