In the Nihonshoki (Chronicles of Japan), there is a description that Koteko, who was resentful about the Emperor whose love toward her had withered away, secretly informed SOGA no Umako of the words the Emperor had said to himself when he saw a boar presented to him, "Some day I will kill the man I hate just like cutting off the boar's head," which triggered assassination of the Emperor.
日本書紀には、小手子が天皇の寵愛が衰えたことを恨み、献上された猪を見て天皇が漏らした「何の時かこの猪の頸を断るがごとく朕が嫌しと思うところの人を断らむ」という独り言を、蘇我馬子に密告したことが、天皇暗殺事件のきっかけとなったという記述がある。