He precisely recorded the details of the two visits of the Envoy Ship Dispatched to Ming China as "Sakugen nyuminki," which is important historical reference material to study and to know about the last days of the trade between Japan and the Ming Dynasty in China.
二度に渡る遣明船往来の詳細を『策彦入明記』として克明に記録しており、末期の日明貿易を知る上での貴重な史料となっている。