The Yami no Matsuei anime is thirteen episodes long.  Central Park Media has secured the rights to the anime, so fansubs are no longer available.  I assume that it'll be released on four different tapes/DVDs, with episodes 1-3 (the Nagasaki Arc) on the first, 4-6 (Devil's Trill) on the second, 7-9 (King of Swords) on the third, and 10-13 (the Kyoto Arc) on the last.  The anime follows the manga pretty closely, although there are a few parts that have been changed; some of these are listed in the Anime vs. Manga section.  There are a few major and minor changes throughout, but overall it's more or less the same.  However, I haven't read the manga for the last section of the anime (episodes 10-13; manga volumes 7-8), so that part isn't up yet. ^^;