The question about what role the emperor played in Imperial Japan is an interesting one, especially when we compare it with the one that he played in the Shogun era. In this earlier era, the emperor was arguably nothing but an outdated figurehead, with the Shogun (a title literally meaning General) was the real source of power in Japan. This was all to change with the Meiji Restoration in 1868.
In theory at least, the emperor, whether that be Meiji, Taisho or Showa, was the ultimate source of power in Japan. The Meiji Constitution of 1889 describes the duties of the emperor as being the ‘head of the Empire, combining in Himself the rights of sovereignty, and exercises them, according to the provisions of the present constitution’. However, the extent to which the emperor actually used these powers and was a force in Japan must also been considered when looking at the role that the emperor played. The fact that it was not Meiji himself who drew up at the important Charter Oath of 1868, an initial document set out by Meiji about how the new restored Japan would operate, is telling of the role which the emperor would play. It was instead constructed by Iwakura Tomomki and Kido Takayoshi. The influence of men such as these, along with other figures such as Itō Hirobumi and Saigō Tsugumichi, referred to as being the ‘genrō’ and how much influence that they held over affairs in Japan is also important when coming to a conclusion about the role of the emperor. These men were often from the old hans (akin to a county) of Choshu and Satsuma and had been influential in the restoration of Japan, and who therefore went on to hold positions of power in Imperial Japan such as the position of Prime Minister. The political crisis faced by the Emperor Taisho in 1912 is also demonstrative of the fact that power on a political level did not lie with the emperor. This was when a politician, Katsura Tarō was accused of having too much influence over the emperor and of a lack of commitment to the constitutional government as laid out by the Meiji Constitution. Donald Keene also points out that it is hard to assess the extent to which the emperor undertook and suggested himself, since he had a heavy reliance on his ministers of state.
If the position of the emperor then was not one which held a vast amount of political power then, what was his role in Japan? The fact that the emperor was supposedly descended from the Sun Goddess Amaterasu and there therefore thought of as being a manifest deity suggests that there was some sort of obligation of the emperor to act in a moral capacity for Japan and be a source of moral authority. For example, the emperor was meant to have responsibility for the actions of the government as part of the Confucian values. The idea of the emperor being the kind and ambivalent spiritual leader as part of the Confucian and Shinto conditions also helped to tie the Japanese together under a shared historical tradition. Due to this position as an exalted figure, it is certainly possible that the role of emperor had to be one which was removed from the political squabbling of the constitutional government in order to retain the role of being a sacred and removed figure. Moral responsibilities for the actions of the government aside, this had the advantage of meaning that the emperor was removed from the blame of things going wrong in the political sphere.
It has been argued by Stephen Large that ‘Meiji was indispensable to this process of political centralization as the symbol of new national consciousness’, especially in the period just after the restoration when a symbol of unity was particularly needed in order to unify Japan after the change in power. The fact that the emperor was assigned a prominent and visible role, very much unlike what it had been in the Shogun era, also helped to make him a popular figure who the people could rally around. Emperors Meiji and Showa in particular went on tours of Japan in order to gain support, and the figure of the emperor became a more accessible figure. This was especially important for the Showa emperor after the Great Kanto Earthquake of 1923 when he toured the city after the disaster in order to show his solidarity with the people who had been affected by it. Under Showa, the image of the emperor also became more modern and publically accessible, especially with the fact that he and his wife helped to popularise the wearing of modern Western dress in Japan.
To conclude, the role that the emperor played in Imperial Japan was one that was mainly concerned with acting as a unifying and moral force. This was a role that was especially important after the Meiji Restoration. The emperor also played an important role in being the source of a Japanese national identity for the restored Japan. So although the emperor probably did not hold much political power in practice, it was what the position of emperor represented, namely the idea of unity, which was ultimately of greater significance in Imperial Japan.
 ‘The Constitution of the Empire of Japan’, <i>National Diet Library</i>, translated by Ito Niyoji, http://www.ndl.go.jp/constitution/e/etc/c02.html#s3.
 Donald Keene, <i>Emperor of Japan: Meiji and His World 1853-1912</i> (New York, 2002), 537.
 Ibid., 722.
 Stephen S. Large, <i>Emperors of the Rising Sun: Three Biographies</i> (New York, 1997), 28.
 T. Fujitani, Splendid Monarchy: Power and Pageantry in Modern Japan</i> (California, 1998), 10.
 Large, <i>Ibid</i>., 29.
Jerold M. Packard, Sons of Heaven: A Portrait of the Japanese Monarchy</i> (London, 1988), 253.