Also, in 867, while he was serving as the lord of Sanuki Province, he published "Fujiwara no Aritoshi moshibumi" (petition by FUJIWARA no Aritoshi), which is the oldest existing so-gana (cursive style writing of Manyo-gana) writing and is currently stored as a national treasure (at Tokyo National Museum).
また同じく讃岐介在任時の貞観(日本)9年（867年）に日本の書道史草仮名の最も古い例としての自筆文『藤原有年申文』が国宝として現存（東京国立博物館蔵）する。