From what little I know of Japan's history and without factchecking, please do so yourself and talk about it in the next episode: The Emperor used to be more of a figurehead than the Emperors of medieval Europe. It was the Shogun, the leaders of the clans of samurai that ruled. Then at some point ( i.e. during the events of the first episode) the Shogunate was replaced by the Emperor + Diet government type. But the Emperor, who also was a religious figure to the people, didn't have a monarch's ultimate power then either. I figure that the plan is "We will tell people that the usurpers of the previous shogunate''s state of government held the Emperor hostage to validate their governance, so when we free him and take him on our side, he will restore the shogunate and you (the guy Buhei's talking to) will be made Shogun."