When the Mongol letter reached in January 1268, Masamura who assigned his regency to Tokimune HOJO in March of the same year assumed the post of rensho again to assist Tokimune HOJO, and also held the office of Samurai-dokoro betto (the superior of the Board of Retainers).
文永5年（1268年）1月に蒙古国書が到来すると、同年3月に執権職を北条時宗に譲り、再び連署として補佐、侍所別当も務める。