Kuroshitsuji II is a story completely apart from the original manga story, and not that good for my taste. You should begin with Kuroshitsuji or Black Butler, and the come here. First you should know that this is the third season of the series. If you are trying to watch Kuroshitsuji Series (Black Butler) for the first time, this is not the place where you should start. Just in case you fall in love with this series like I did! (Both animated projects are canon and follow after Circus Arc (in order of story-line)) there are two OVA's that follow this arc called 'Black Butler: Book of Murder' that are already out as of 2014 and a feature length film after that called 'Black Butler: Book of Atlantic' hitting America theaters June 2017. I totally recommend you watch this because of the art and characters, although it can be a little bit on the darker side of things it still has some funny moments and seriously good story plot that just makes you want more! I freaked out when I heard that they were doing this season to follow the manga and get Yana Toboso's actual story-line animated! I think the best points of Circus Arc is how it touches base with Ciel's backstory more and the over-all plot of Black Butler, while still having the Black Butler 'mysteries' that are solved by the Queen's Guard Dog! Even if you didn't watch the first season there isn't much confusion if you wanted to just start with this, it's very well made that you could follow it easy. So everything in the second season was the 'anime story-line' and not the 'canon/manga story-line' like Circus is. To put it simply, this is the canon part (following the manga) that occurs right after the Curry Arc in season one. Some people can be confused by this 'third season' if you watched the first and second season of Black Butler.

Gaara relationships.First off, I'm sooo happy that Crunchyroll put out this season of Black Butler! The art style has really improved and really does these characters justice.

Is black butler season 2 canon