Who did samurai's serve?
Answer 1:
SAmurais served their Shogun. A shogun was the military leader
and as the years went on shogans became more incharge then the
emperors.
Answer 2:
Samurai didn't serve the shogun, they served the daimyo, the
Japanese lords. Then the daimyo would give the shogun loyalty and
the service of some of the daimyo's samurai, in return for land
which they gave some to the samurai.
The shogun has (for example) 3 lots of land - A, B, C. Two lots
of samurai -A,B - serve the daimyo.
The shogun gives land lot B and C to the daimyo in return for
samurai lot B. The daimyo gives land lot C to the samurai in return
for their service.
So even though samurai lot B 'serves' the shogun, they actually
do that only because they serve the daimyo.