It is said that Yoritomo was assassinated like his sons, MINAMOTO no Yoriie and MINAMOTO no Sanetomo, which was not written in Azuma Kagami in order to hide the fact.
頼朝は子の源頼家や源実朝と同じく何者かに暗殺されており、その事実を隠すべく吾妻鏡への記載を避けたとする。