Juubee Ninpuuchou: Ryuuhougyoku-hen

ZOMG~ This doesn't compare to your AVERAGE ninja anime series. I do admit that both series are too short but both has your very true ninja styles, fight scenes, gore, violence, blood and of course good characters and storyline. 

Ninja scroll and afro samurai are similar in terms of the bloodshed.. and samurai swording.  

A wandering samurai helps a princess, killing lots of shinobi along the way. The same unique 90's art style is prevalent, and the action is similar, although Ninja Scroll has more polish. Note this is a series based on a movie by the same name-both are good/relevant. 

Both of the series are set in feudal japan has a samurai protagonist with a similar story of protagonist protecting a girl. Antagonist are super power user. Lot of blood and gore is involved. yasuke has more of mecha and American feel. While ninja scroll series on the other had more ugly horror appeal 

Samurai Japan dark fantasy about ninjas with supernatural powers fighting against demons and evil magic conspiracy. Bloody and naturalistic fights.  

another 13 ep series with an easier story to follow. Better animation too. 

Both have alike action style (maybe because of the same director), both are full of manlyness and similar dark humour. Also, the main boss in both is the same big fat guy. 

A brave and extremely skilled warrior suddenly finds themself protecting a young heir to the nearby feudal province who is also somehow a key to a local magical event. From time to time they are accompanied by a strange old person with shamanic powers. There is some well-choreographed fighting which is probably the main attraction because everything else is kind of bland. 

Both have similar story;and are full of action. 

Both series are produced by Madhouse and that's why art is almost identical. Kurou bears a strong resemblance to Jubei because of his battling style and antagonists' designs are very much alike.