In short, the second season of Reikenzan seems to be vastly different than the first one. The first season was more like the protagonist's journey to become a powerful disciple, and on his journey we get to know more about the friends he make, see his training arc etc. It was more happy-go-lucky in tone. The second season however feels a lot more darker. We get to see the protagonist coming back to his village and facing some issues there, and while trying to solve them we see how our hero has to play a lot of mind games, and even some big real battles! Heck, at one point we see a damn bloody battle that turns it into a horror show! Of course, the comedic tone is still present there, but it's much darker this time.
If we consider the story, it might fail to charm a big part of the viewers who enjoyed the first season, and that's understandable. The tone of the story shifted heavily, and that will cost dearly for some of the audience. I however enjoyed it. It is not anything spectacular, or might not be on par with the first season, still it felt enjoyable.
This might be another deal breaker for some, since the character designs changed a lot, sometimes to the point when some of the previously established characters felt unknown. The first season had the character designs in a, let's just say, pointy style. A lot of sharp angles were present as a facial feature, and it felt kind of unique. The second season's character designs are smooth, and instead of those pointy angles we see round edged broader faces. The same studio is behind both seasons, and the difference between the airing date of these two seasons is not even that much, just a year. Yet they feel so different. Still, they didn't look anything near being bad. The background environmental arts are beautiful!
The BGMs are good, nothing special but doable. The opening and ending tracks are okay. The sound effects are, again, nothing special.
A very small part of the characters from the previous season returns this time, and the saddest thing is that the most fan favorite character Oubu has more like a cameo in this season. Ouriku, Rei and Bunhou were the main focus, along with two new and (almost) main characters (and I beg your pardon since I totally forgot their names, but you'll know the ones I'm talking about, nothing spoilery here). Ouriku-Rei-Bunhou's characters were already developed the previous season, so all we get to see is how they act this time. The only growth we see is that of Ouriku's. The two new characters that I mentioned were more to the comedic aspects of the story, and I enjoyed their onscreen presence. As for the others, they were merely there for the plot.
I will say it, I enjoyed it. The mind games that Ouriku play were interesting, and some of the actions he takes were pretty amazing if if they were brutal.
Overall, even if I won't say it is as good as the first season, it still gets close to it. Different, but enjoyable. Looking forward to a third season if it ever comes out.