According to the tradition, they were contributed to Kangakuin (educational institution) by FUJIWARA no Fuyutsugu and possessed by successive Toshi choja who doubled as betto (chief officer) of Kangakuin for generations.
伝承によれば、藤原冬嗣が勧学院に納めた物とされ、以後代々勧学院の別当を兼務した藤氏長者が所持していたとされている。