Each nation tends to have powerful individuals as their most powerful military force.
In the Sternbild Kingdom, these are the Four Symbolic Heroes. In addition to them, Avenger was a member of the kingdom and eventually might have joined as a fifth hero.
In the Kirika Empire, the Eight Great Knights, together with the [Divine Priestess] serve this role, and together are roughly equivalent to the kingdom's four heroes.
In addition to these heroes, there are certain others who are roughly equivalent, primarily Otherworlders.