宋书
Since Bu is most likely to be Yūryaku, Kō, who is said to be Bu's older brother, is likely to be an equivalent of Ankō, who is also noted in the "Nihonshoki" as an elder brother to Yūryaku. However, the "Book of Song" records Kō as ""Crown Prince" Kō"; there is a possibility that he is not Ankō, but rather Prince Kinashi no Karu, who was a crown prince of Ingyō.