Considering HanIro is around 26-episodes or so, I'm pretty sure they are pacing the character development to fit around that level of pacing, the latest episode is actually a good example of how they are going slow down the development to a crawl to fit for the long-haul.
Also i disagree with the sentiment that Minko has no potential for development or has had none throughout the entire series thus far.
Also i disagree with the sentiment that Minko has no potential for development or has had none throughout the entire series thus far.