In 887, when he was a Monjo Hakase (professor of literature), he discovered letters regarding "Ako" (another name for Sessho (regent) or Kanpaku (chief adviser to the Emperor)) in the Shochoku (imperial edict) and they were from Emperor Uda to Mototsune written by Tachibana no Hiromi, saying that "Ako is merely a title and without substance or official duties" which caused the so-called "Ako Controversy."
文章博士の地位にあった仁和3年（887年）、橘広相が作成した宇多天皇から基経への詔勅にあった「阿衡」の文字に関し、「阿衡には位貴しも、職掌なし」という見解を発して、所謂「阿衡の紛議」を引き起こした。