There's quite a bit of true things being said here.
Someone remarked that this is an arc that we should like but don't. That's exactly how I feel about it. It's, while predictable, an arc full of potential that seems to remain unused, moreover it feels wrong for reasons I can't yet explain.
I had a moment of joy when Kenichi hit Miu in the face and shattered her mask, only to see that he didn't actually hit her. I think Kenichi finding the resolve to seriously attack Miu would have been a small mark of character growth for him. But since it's in the focus of this thread, lets dive into Kenichi's growth a bit deeper.
One of the small but nice point we see in this arc is Kenichi becoming inceasingly used to the atmosphere of the underground fighting world. He might still be intimidated, but he begins to retain his ability to act. It's a small thing, but we should notice it because one of Kenichi's most crucial weak points is his mental state.
There's something else about Kenichi that we can deduce from the portrayal of his fights. At the beginning of the manga, Kenichi knew a small amount of techniques which were called out to us, and used very basic nameless punching and kicking techniques for the rest. In the newer fights, Kenichi still uses techniques, but they blend into the background, no longer being worth of being called to our attention. It has been a long time since Kenichi learned specific techniques like they were introduced all the time at the beginning.
The last technique he learned was the Korui Nuki, which isn't very interesting as a technique itself, but allows for interesting moments in the fight by virtue of pointing out the weak points in the opponent's guard. Note however, that learning the Korui Nuki required Kenichi to master his center of gravity completely. Kenichi's way of moving is beginning to transcend into the realm of superhuman, which is a clear mark compared to the very interesting scene when he and Miu entered Diego's ship and Miu just walked up the chains while he climbed. Now he probably could do that as well. It's the first really distinct step into the advanced ways of moving that the masters use.
Back to the techniques. There are more or less only two attacks of Kenichi that are still called out. One is the Mubyoushi, the other the Korui Nuki. (The Seikuken and Ryusui Seikuken might be as well, but those are rather passive techniques.) We have just discussed the Korui Nuki, but lets have a lot at the Mubyoushi, since it's actually a much more important step in Kenichi's growth.
What has been called out, and rightly so, is that Kenichi's fighting progress is divided between mental and physical. Kenichi learns stuff from his masters and uses it (and even that is getting rare now), but he does not really advance his understanding of martial arts. But the Mubyoushi is the one thing standing against this. It is the only technique Kenichi ever developed by himself and it has been by far his strongest one until the advent of the Korui Nuki. It is a technique symbolic to his growth as a fighter, since it combines the basics of all his punching styles by his own understanding of their workings. It's the first piece of the combined style we are waiting for him to develop. This is what has to happen more often, and it is behind schedule.
Note also how most of Kenichi's special techniques, save the ones he learned at the very beginning (which we don't see that much anymore), are not so much specific moves as passive ways of moving. The Seikuken and Ryusui Seikuken are about controlling his space and reading and controlling the opponent's rythm. The Mubyoushi is a way of punching that combines multiple ways of generating force. The Meotode is a way of moving both hands in a synchronized fashion. The Korui Nuki is, although portrayed as a kick up until now, the principle of forcing the opponent to guard and then breaking through the guard's weak points. These are all fighting principles rather than fighting techniques.
This very much conforms to the master's idea of making Kenichi a fighter who rules through the complete mastery of the basics. Kenich isn't supposed to learn advanced techniques, he is learning advanced principles of fighting that are expressed by using the basics more effectively.
The Mubyoushi is how every of Kenchi's punches is supposed to work at his completion. The Korui Nuki is what he will do every time an opponent guards. He will always be in the Ryusui Seikuken mode. Unfortunately this makes for less interesting fights, but that's why these new principles are shown to us in the form of techniques. If you compare an early fight with the fight against the Muay Boran kid whose name I just forgot you will see that the latter fight has a lot of very nice fighting panels without any technique being called out, simply because they all integrate passively into Kenichi's basic style.
However, to achieve this ultimate integration, this mastery of basics Kenichi himself has to step up again and further his own independant understanding of his martial arts. This isn't something he can learn (although he can practice for it). It's one of the parts of seriousness Kenichi is so sorely lacking, the drive to work and think on martial arts independently instead of just repeating his master's exercises. We know he can do it, and when he did it was a major jump in power for him. Most of his important fights were won with this technique. But we don't see any of this inspiration right now. Kenichi has been watching his master's fights for quite a while by now. Hopefully it will get him thinking.