The power structure of the Samurai age of Japan is most similar to what system in Medieval Europe? Feudalism ? Caste System ? Democracy ?

Feudalism

Explanation:

During the Samurai era, Japan still had an emperor but was effectively ruled by a Shogun who maintained military control over the country. In order to rule, they relied on the support of he various samurai leaders in different parts of the country.

This was very similar to the Feudal system in Europe where local lords held significant power in a kingdom because they controlled their area and so the Monarch needed their influence to exert control over the whole nation.  

it is

a

asked for and recieved from the united states

the answer is states.