Hakuouki: Hekketsuroku

There are many touching deaths in both anime's although Hakuouki has a little non-fiction in it both have plenty of fighting and many unsolved mysteries. 

Same situation with a girl that is 'adopted' into a clan with male warriors who are at war. Both are reverse harems in a way 

Listen to me guys, this is what being a true man is about! Protecting the girl you love. I really admire Kenshin and Hijikata. Epic anime!!! 

Both deal with supernatural beings ( Vampires and Oni ). Also, all the Oni look very much like Zero and the main characters have a relationship 

No question: Wolf's Rain is the superior anime, but they do have a bit in common. Both center around a group that is seen as a menace to society and which the audience is meant to root for. Both also boldly kill off an almost unbelievable number of characters. You watch these individuals succeed through many trials, then suddenly that changes and one by one, they're systematically killed. The shift is quite sudden in both cases, but even more pronounced in Wolf's Rain. Obviously, watching the first season of Hakuouki is necessary, but the large amount of character death happens in season two, thus this recommendation. Frequent action and attractive character designs feature in both as well. read more 

Both are about war between clans. While in Basilisk they´re ninjas, in Hakuouki they´re samurai. Both deal with tragedy. Both are also about a forbidden love.