Gabriel makes a good point about setting. While sometimes in feudal Japan, subordinates did bow their lords on the battlefield, the most often case was a nod of the head and off to do those orders. Especially since those things were often time sensitive.
Since we're pressing each other for votes, my vote is to allow both. Both have a place in post-1868 Imperial Japanese military. To use feudal models would be extremely inaccurate for the kind of atmosphere Yamatai seems to have. That is: unified, militaristic, and dominant.
The presence of the Elysian suzerainty makes the parallel stronger. Feudal Japan was never truly united, even under the Tokugawa. The idea of a single nation-state only emerged in practice after 1868. A country divided into clans, and their rivalries, cannot effectively govern colonies abroad. A centralised government can, which the EoJ was.
Another thing - each planet does not maintain its own army. There's only the Star Army. To use a feudal model, each clan or however we wish to divide ourselves (planet, system, etc), must have its own soldiers who owe primary loyalty, not to the Empress but to their local lord.
@ShotJon, perhaps what I say is too in-depth but I cannot stand to see people talking about another culture like they are intimately familiar with it. Even my brief message is a huge oversimplification of the periods I mentioned, with many omissions.
It is also necessary to establish whether this is pre or post-Meiji because Japan almost entirely abandons its feudal traditions after 1868. What took Europe hundreds of years to do - move from a feudal to an industrial state - took Japan a few decades. In 1895, they trounced the Qing Dynasty in China, the only superpower in Asia ever up till that point. In 1905, they destroyed two Russian fleets and forced the Russians to give them parts of Manchuria. And we all know how much fighting it took to defeat in WW2. In 100 years, Japan went from swords and bows to battleships and machine guns. Few nations have ever transitioned so rapidly and Japanese society is STILL feeling the effects of that rapid industrialization and westernization.
So, establishing historical basis is necessary because it tells us what kind of Japanese culture we're looking for.