Miyohajime refers to a series of measures and the policies that are performed as part of the rule of the new reign of the new monarch at the beginning of his assumption after the death or retirement of the previous monarch.
A new monarch needed to understand the people; at the same time, the people expected that the old system would be reformed or abolished under the new monarch. During the Middle Ages, they were done in the form of 'tokusei (benevolent rule) of miyohajime' from the monarch to the people, and in the form of demonstrational actions from the people to the monarch such as the uprising of tokusei to demand the enforcement of tokusei.
In the Edo shogunate, after Hidetada TOKUGAWA was appointed as the second shogun, his father, the former shogun, became Ogosho (leading or influential figure) and continued to take control of actual government affairs for almost 10 years, and after his son, Iemitsu TOKUGAWA, was appointed as the third shogun, he also became Ogosho and continued to take control of actual government affairs for almost 10 years. For this reason, immediately after the death of a father, Ogosho, declaring Miyohajime was the way to show the attitude of actively engaging in the government affairs. As a result, it became customary to develop the new policy of Miyohajime at the time of the assumption of the new Tokugawa Shogunate family taken place due to the assumption of Seitaishogun (commander-in-chief of the expeditionary force against the barbarians, great, unifying leader) or the death of Ogosho.
The famous reformations of the shogunate government, 'the three biggest reformations' (the Kyoho reform, Kansei Reform, and Tempo Reforms) are part of 'Miyohajime' by Yoshimune TOKUGAWA (8th), Ienari TOKUGAWA (11th), and Ieyoshi TOKUGAWA (12th); the Ansei Reform and the Keio Reform can both be associated with the 'Miyohajime' of Iesada TOKUGAWA (13th) and Yoshinobu TOKUGAWA (15th) (the Bukyu Reform is thought to be associated with Edo geko, go down to Edo, of the Imperial envoy of Emperor Komei, but not with 'Miyohajime.')
In the local regions, there were high expectations for 'Miyohajime' when there was the change of family heads or feudal lords.