Mansai (1378−1435) was an abbot of the Daigo-ji Temple in the early Muromachi period (14th−15th centuries). Born into an aristocratic family, Mansai was adopted by Shogun Ashikaga Yoshimitsu and ordained into the priesthood. He served three shoguns, not only as a priest but also as a political adviser and close associate. Mansai witnessed many important events in politics, foreign relations, literature, and society and was privy to the top secrets of the nation. Mansaijugō nikki (The diary of Mansai) is thus an important historical source. The National Diet Library has the part of the diary covering from the 18th to the 29th year of the Ōei period (1411−22). The diary entries for each day are written on the reverse side of an annotated calendar. The document was originally in scroll form but was later changed into 11 volumes of accordion books. Its form was later restored to 11 scrolls. The Sampō-in Abbey of the Daigo-ji Temple has the part of the diary (38 volumes) covering from the 30th year of the Ōei period (1423) to the seventh year of the Eikyō era (1435).