It is said that ancestors of Joshi KOKUSHI were the Baekje royal family, and Uija, who was the king when the Baekje Kingdom fell, must have been relatively closely related to Kokushi.
黒歯常之の祖は、百済の王族であり、黒歯常之もさほど百済滅亡時の義慈王からみて遠い同族ではなく、比較的近い親族であったと思われる。