As far as art goes, this is the cutest Rika that has been drawn so far, maybe it's the fact that she is younger than in the other arcs.
This arc was very different than the others, taking place before the Oyashiro's curse has started, and the Dam project war is still happening. I really liked that this arc is so different than others, sadly only two episodes of this arc were put into the anime and I liked seeing other stuff that happened. This arc seems to be overlooked a bit, but i say that it should be read.
