In the "Heike Monogatari," it is said that the purpose of the marriage of Tokitada's daughter with Yoshitsune was to steal a secret document, but the reason why Yoshitsune agreed is not clear.
時忠の娘と義経の婚姻について『平家物語』は機密文書の奪取が狙いだったとするが、義経が承諾した理由は不明確である。