In 1559, when Kagetora NAGAO (later Kenshin UESUGI) of Echigo Province went to Kyoto, he became close to Sakihisa and they made a pact by exchanging vows written in blood.
永禄2年（1559年）、越後国の長尾景虎（後の上杉謙信）が上洛したが、前久と景虎は互いに肝胆照らし合い、血書の起請文を交わして盟約を結んだ。