Through the influence of his relative who worked as a wet nurse of MINAMOTO no Yoritomo, Yasunobu, known as a competent government official, was invited from Kyoto to Kamakura to assume the role as the first head of the monchujo.
康信は有能な役人として知られていたが、親類に源頼朝の乳母がいた縁もあって、初代執事として京都から鎌倉へ招かれたのである。