The story line is actually amazing people just don't understand the symbolic meaning of what is really happening. Nanno represents karma and Yuri represents revenge and anger.
In the liberation episode or some other episode Nanno wears a green ribbon which represents balance and Yuri wears a red ribbon which represents destruction. There has to be a good and bad to balance out each other. In the last episode Nanno is mortal or something ( people are actually debating it you can check it on YouTube videos related to this series) when people think revenge is the only option karma just fades away . Karma acts as if it is gone but waits for the destruction caused by revenge. But I agree this message should be given in the end of the series itself so that people don't get confused.
It was a interesting series . I have never seen a series that is based on karma as the main lead.
Sorry for my bad English as it isn't my first language.(it is not exactly a review but something I wanted say)