Kiyoyuki MIYOSHI successfully proposed a change of era name to the emperor based upon Shinisetsu (a periodical prediction theory, a Chinese theory explaining that extraordinary events will happen in the years of kanototori (辛酉) and kinoene (甲子)) and after that the era name was changed to Engi, it became customary to change an era name back then, based on the cyclical disaster theory to avoid disasters and uprisings.
讖緯説（しんいせつ、周期的予言説辛酉・甲子の年には革令があるとの中国の説）にもとづいて改元を上奏して認められ、元号が延喜と改められて以降、周期的災厄説による辛酉年・甲子年の災異改元が通例となった。