In 650, when a white pheasant was presented by Kokushi of Shirato Province, on the basis of a precedent in which the appearance of an uncommon bird was considered as an auspicious sign written in an isho in the Han period in China as well as in Chinese books on history, So MIN submitted a jonzui kaigen (a principle of Onmyodo which suggests a new era name be established when a phenomenon considered as a lucky omen occurs) to Emperor Kotoku urging that 'since heaven presented an auspicious sign responding to the Emperor's virtues, a general amnesty should be granted to the entire nation,' thereby the imperial era name was changed Hakuchi (white pheasant) and he remained in an important post until his death in 653.
その後も、650年（大化6年）に白戸国司から白い雉が献上された際、珍鳥出現の祥瑞を中国漢代の緯書の語句と中国の史書に見られる先例を根拠に「帝徳が天に感応して現われた祥瑞であるから天下に大赦するべきである」と孝徳天皇に祥瑞改元（吉兆とされる現象をもって新しい年号をたてるべきであるとする陰陽道思想）を上申して取りいれられ、元号が白雉と改められるなど、653年（白雉4年）に病没するまで重用された。