Ever since the Meiji Constitution and the 1889 Imperial House Law were established, emperors have stayed in their position until their demises. Japan's first prime minister, Hirobumi Ito, who was instrumental in drafting the Meiji Constitution, argued during a meeting in 1887 that once someone ascends to the Imperial Throne, they have no justification to abdicate at will. He saw the emperor as being "a pillar of the state" with complete control of sovereignty, but designed a system in which politics would not be affected by the will of an emperor. In addition, a manual on the 1889 Imperial House Law issued by Ito, pointed out that the Nanbokucho civil war that took place in the early Muromachi period was the result of the then emperor being forced to abdicate by vassals that had built up their own power.
The emperor's status also came into question after Japan lost World War II. In 1946, under the occupation of the Allied Powers, abdication rose as a topic in the Imperial Diet. However, then Minister of State Tokujiro Kanamori argued that "when carrying out symbolic responsibilities under the consensus of the Japanese public, one cannot abdicate based on the individual's circumstances." He also said, "For an emperor, the personal does not exist."
[…]
In his video message released on Aug. 8, Emperor Akihito [...] emphasized that as a symbol, it is important for the Emperor -- especially in the modern Heisei era -- to be and work "with the people."
One conservative constitutional scholar has expressed concern, however, saying, "His Majesty the Emperor is industrious and has expanded his public duties, but the more one raises the bar on what it means to be a symbol, the harder it gets for the next generation of emperors."