In August 1264, following the 6th Regent Nagatoki HOJO's entrance into the priesthood, Masamura HOJO became the 7th regent, and in August of that year, Tokimune, at the age of 14, assumed the position of rensho (assistant to the regent).
文永元年（1264年）7月、6代執権北条長時が出家、北条政村が7代執権となり、8月には時宗は14歳で執権の補佐を務める連署に就任する。