Taira no Masakado History . Masakado was born into a prominent noble lineage , the Kanmu Heishi ( or Taira clan descended from Emperor Kanmu ) . He served the imperial court in the capital as a youth , and then settled down to the life of a country gentleman in the provinces of eastern Japan , to the northeast of modern day Tokyo . His career is detailed in " Shōmonki " ( " The Masakado Chronicle " ) , a literary account of his life believed to have been completed as early as the 940s ( although the earliest surviving copy dates from 1099 ) by an anonymous author . The Taira Masakado Insurrection of 939 - 940 ( known in Japanese as " Jōhei - Tengyo no ran , " after the calendar eras in which it occurred ) ranks among the most dramatic episodes in the early history of the samurai . Coinciding with earthquakes , rainbows and lunar eclipses in the capital ; uprisings in the north ; and pirate disturbances in the west ; it threw the court and the capital into a panic , and climaxed , according to most versions of the story , with the protagonist ’ s claiming for himself the title , “ New Emperor . ” Many historians have perceived the incident as an early harbinger of the late twelfth - , thirteenth - and fourteenth - century events that , step by step , ushered in the medieval era of warrior rule . The drama began in the second month of 935 , when Masakado was suddenly attacked — ambushed — by another prominent local warrior , Minamoto Tasuku ( dates unknown ) , at a place called Nomoto , near the convergence of Hitachi , Shimozuke , Musashi , and Shimōsa provinces . Tasuku was the eldest son of Minamoto Mamoru , a powerful warrior and sometime government official of Hitachi . The reason for his grudge against Masakado is unclear , but his decision to pursue it in the field set in motion a complex and momentous chain of events . Within months Masakado found himself at war with several of his relatives . Although taken by surprise , Masakado defeated Tasuku , and then struck back , burning and plundering the homes and property of Tasuku ’ s supporters across southeastern Hitachi , and slaughtering thousands of the residents of these compounds . Among the most important victims of the Nomoto battle and its brutal sequel were Tasuku , his brothers , and his brother - in - law , Taira Kunika ( ? - 935 ) , who was also Masakado ’ s uncle . Their deaths brought Masakado into conflict with two of Mamoru ’ s other sons - in - law , Kunika ’ s son Sadamori ( dates unknown ) , and Masakado ’ s paternal uncle and father - in - law , Taira Yoshikane ( dates unknown ) . During the next four years Masakado took great pains to remain within the boundaries of imperial law . In the ninth month of 936 , he received a summons to appear at court to answer charges filed by Minamoto Mamoru , but was able to convince the Office of Imperial Police and the Council of State that there were mitigating circumstances for his actions , and escaped punishment . Two months later , he was pardoned entirely , when the court declared a general amnesty to commemorate the emperor ’ s coming of age ceremony . Masakado returned to Shimōsa , but was soon once again at war , this time with his father - in - law , Yoshikane . A series of raids and counter - raids climaxed in an attack on Masakado ’ s home at Iwai , in Shimōsa province . Yoshikane ’ s troops surrounded the compound just before dawn , trapping Masakado inside . Amazingly , Masakado drove Yoshikane off , killing more than half his troops . Yoshikane himself escaped , but died a year and a half later of an unidentified illness . In the meantime , Masakado managed to secure legal sanction for his part in this quarrel in the form of a warrant issued by the Council of State directing him to apprehend Yoshikane , Mamoru , Sadamori , and others . Early in 938 , however , Masakado received a second Council of State summons for questioning over another quarrel with his cousin Sadamori . But this time he ignored the order entirely . Acting on the premise that the 937 warrant against Sadamori was still in effect , Masakado led troops to the Hitachi provincial government compound to arrest his cousin , but Sadamori escaped before he arrived , and hid out in the mountains for several months . In the eleventh month of 939 , Masakado again entered Hitachi at the head of a large force , ostensibly to plead with the provincial government on behalf of one of his followers . Whatever his intentions might have been , he ended by attacking and occupying the provincial government headquarters , and , with this action , crossed the proverbial line . He was no longer just a provincial warrior feuding with local rivals ; he was now a criminal , in rebellion against the state . Seeing no avenue of retreat , Masakado chose instead to surge forward , seizing , in rapid succession , the government headquarters of Shimotsuke , Kōzuke , Musashi , Kazusa , Awa , Sagami , Izu and Shimōsa provinces . Intriguingly , his next move was to dash off a letter to his patron , the Prime Minister , Fujiwara Tadahira ( 880 - 949 ) , insisting that he had been unjustly maligned and defamed by his enemies , and that he remained at heart , loyal to the law . The traditional view , outlined in " Shōmonki " , describes his takeover of the east as the first step in a campaign to make himself ruler of the entire country . " Shōmonki " depicts one of Masakado ’ s followers coming to him with a proposal that , having already made himself an outlaw by striking down one province , he might as well annex the rest of east . It further portrays Masakado receiving an oracle that confers on him the status of emperor , after which his confederates style him the “ New Emperor , ” and Masakado goes on to appoint a new court and bureaucracy and lay plans for building a new imperial palace in Shimōsa . It is unlikely , however , that any of these events ever occurred outside the imaginations of the " Shōmonki " authors . Not only would they imply the sudden onset of a level of arrogance dramatically at odds with Masakado ’ s behavior before and after these incidents , but the title of “ New Emperor , ” the oracle proclaiming Masakado ’ s ascension , the building of a new imperial palace , and the naming of new central government officials appear only in " Shōmonki " and texts derived from it ; they are not mentioned in any of the court ’ s proclamations or other records of the Masakado affair — which is exceedingly odd , in light of the frenzy and paranoia that gripped the court in 940 , if Masakado really did any of these things . More probably , Masakado ’ s intent , in the wake of the debacle in Hitachi , was to establish a position of strength from which to take advantage of the court ’ s preoccupation with natural disasters , bandit activities in the northeast and the capital region , and pirate troubles in the west , and negotiate some form of pardon . Nevertheless , within a month , the court had issued edicts calling for Masakado ' s destruction and commissioned several warrior notables for this task , including Sadamori and a sometime ally of Masakado ’ s , Fujiwara Hidesato ( dates unknown ) . On the fourteenth day of the second month of 940 , the government army caught up with Masakado in northwestern Shimōsa province . Outnumbered more than ten to one , Masakado ’ s troops were routed and he was killed . On the tenth day of the fifth month , Hidesato and Sadamori delivered Masakado ’ s head to the capital , where it was hung for display outside the east market . According to legend , the head later took flight on its own , landing in Shibasaki , a small fishing village on the edge of the ocean and the future site of Edo , which later became Tokyo . It was buried . The " kubizuka " , lit . " grave of the head " , located in the present day Ōtemachi section of Tokyo , was on a hill rising out of Tokyo Bay at the time . Through land reclamation over the centuries , the bay has receded some three kilometers to the south . Deification . When Masakado was preparing for his revolt , a vast swarm of butterflies appeared in Kyoto , a portent of the upcoming battle . Over the centuries , Masakado became a hero and even a demigod to the locals who were impressed by his stand against the central government , while at the same time feeling the need to appease his malevolent spirit . The fortunes of Edo and Tokyo seemed to wax and wane correspondingly with the respect paid to the shrine built to him at the " kubizuka " — neglect would be followed by natural disasters and other misfortunes . Hence , to this day , the shrine is well maintained , occupying some of the most expensive land in the world in Tokyo ’ s financial district near the Imperial Palace . Other shrines which he is deity of include ( located in Kanda ) , and Tsukudo Jinja ( which has multiple locations . ) His tomb ( which contains only a monument to his head ) is near exit C5 of Tokyo ' s Ōtemachi subway station . Nussbaum , Louis Frédéric and Käthe Roth . ( 2005 ) . " Japan Encyclopedia . " Cambridge : Harvard University Press . 10 - ISBN 0 - 674 - 01753 - 6 ; 13 - ISBN 978 - 0 - 674 - 01753 - 5 ; OCLC 48943301