"Saimen no Bushi" referred to a group of warriors who attended Daijo-tenno (the Retired Emperor) by guarding and serving the emperor during the Kamakura period.
西面武士（さいめんのぶし）とは、鎌倉時代、太上天皇に仕え、身辺の警衛、奉仕などにあたった武士集団のこと。