the feudal lord can not be expected to deal with every threat to the nation directly. that is why the Hokage is appointed to deal with military matters while at the same time, generating wealth with every problem.
I think the portal is not a problem. I see when I step into it, from my spawning location, I get teleported instantly, but if try and use the teleport to go back to the spawn location. There is a delay. I think the delay is intentional but of course your can tell me if that's the case or not.
I do notice there is like a glow effect, meaning maybe like the portal is charging up