Asano, who was a disciple of sonnoka (person with reverence for the emperor) Soko YAMAGA, was enraged because Kira interfered in the matter of succession to the Imperial Throne (Genroku kaikyo roku [Record of the Valiant Vendetta of Genroku]).
吉良が皇位継承問題に介入したため、尊皇家・山鹿素行の門下である浅野が怒った（元禄快挙別禄）。