I generally enjoyed Shigurui
for its frank and unapologetic interpretation of the post-Sengoku culture of feudal Japan. Specifically, the manga accomplishes the task of scrutinizing the brutality and trivialization of human life that a medieval feudal institution would encourage. I've searched for reviews of the manga and the anime online, and it seems that this series isn't very well known. The anime particularly suffered from bad reviews largely because of what people perceived to be gratuitous violence and sexual assault. It also doesn't help that the anime only covers roughly the first half or so of the manga. As a result of the odd pacing and the introspective nature of the anime, many people were turned off to it, citing it as incomprehensible. I didn't gather every little plot detail the first time I saw it, but reading the manga clarified quite a bit in terms of the characters' motivations and the central conflict. Read the manga to fully appreciate the story because the anime, while visually beautiful (if not alarming in its approach to the portrayal of human anatomy) does not do the story justice.
As someone who studies martial arts, I could see the significance behind the politics of the hierarchy. Shigurui
sets itself up as a not-so-distant critique of the feudal warrior code known as bushido. The author appears to have gone to great lengths to provide a narrative context in which bushido as a concept, as an ideology and as an institution is dissected and shown for what it really is, especially in the hands of malevolent authorities who couldn't care less about the physical, emotional and mental sacrifices of those below them. I'm not opposed to bushido per se, but the opening chapter wonderfully sums up this warrior code as a political legitimization of a sadist-masochist relationship, that is, between the retainer and his samurai. This is a refreshing response to a naive glorification of feudal Japan.
The gore, sex and insensitivity demonstrated by many characters is apparently what kept the series from gaining any widespread appreciation, and some of the criticism is justified. Its historical, psychological and physiological attention to detail is both its greatest success and one of the main reasons why people tend to find it disgusting, vague and pointless. Be patient with this one.