Haseo studied under MIYAKO no Yoshika, SUGAWARA no Michizane, and OKURA no Yoshiyuki, and participated in the compilation of the 'Kanke goshu' (Later Collection of the Sugawara family), and was also involved in the compilation of the 'Engi Kyakushiki' (the Engi Codes).
都良香（みやこのよしか）や菅原道真や大蔵善行（おおくらのよしゆき）に師事し「菅家後集」の編纂に携わり、「延喜格式」の編纂にもあたった。