Accepting the complaints of appeal by Tsunemoto that Prince Okiyo, Takeshiba and Masakado were plotting a rebellion in conspiracy, Daijo daijin (Grand Minister of State) FUJIWARA no Tadahira, Masakado's lord, sent an envoy to Togoku (the eastern part of Japan, particularly the Kanto region) after issuing a migyosho (documents for informing of decisions made by third or upper ranked authorities) to investigate whether the complaints were true.
経基は興世王と武芝と将門が共謀して謀反を謀っていると訴え、将門の主人の太政大臣藤原忠平が事の実否を調べることにし、御教書を下して使者を東国へ送った。