Emperor Seiwa
With the Regency, what was already an unusual situation became even more anomalous when the Hōjō usurped power from those who had usurped it from the Emperor, descending from Emperor Kōkō, who usurped it from the children of Emperor Seiwa. The new regime nonetheless proved to be stable enough to last a total of 135 years, 9 shōguns and 16 regents.