Azuma Hyakkan is also called Souma Hyakkan, and there is a legend that these names were introduced as a government post system by TAIRA no Masakado when he named himself a new emperor and formed a new government.
別名、相馬百官ともいい、平将門が新皇を称して新政権樹立を図った際に設けた官職体系であるという伝説もある。