i forgot but arent samurais are hired mercs, so basicaly ye olde japanese officials dont actually have military division, instead they hire samurai to fight for them
It's a bit more complicated than that, they were basically their own social caste separate from commoners. The status quo changed many times over the centuries but during Ginko's time, the Warring States Period, the central government was essentially powerless and the island was divided into dozens of what were effectively independent states, each with their own local army, all fighting each other for power. By body count these armies were mostly commoner footsoldiers; samurai did fight, but they were also generals and governors for their lords (I don't think Ginko's father taught her about those jobs lol).
They were indeed paid employees technically speaking, but there was also a certain loyalty expected. There were plenty of betrayals and defections of course, but they weren't taken lightly. You had better be sure you're defecting to the winning side, and that your new boss doesn't have any reason to think you would betray them as well.