When Yoritsune KUJO let his son Yoritsugu KUJO succeed the shogunship in 1244, Mitsumura was added as one of the Kamakura bakufu hyojoshu (a member of Council of State) for the purpose of giving support to the new shogun.
寛元2年（1244年）に九条頼経が息子九条頼嗣に将軍職を譲ると、光村はこれを補佐する意図を以って鎌倉幕府評定衆の一人に加えられた。