A couple friends of mine have been asking me if I've read any good manga / watched any good anime lately. They're pretty new, so this is the first title I recommended to them.
I rarely ever, EVER, give out "5 stars" for any manga/anime or books. I think Harry Potter is one of the few that I loved so much as to give it the full five -- even legendary FMA was only four ( >.>;; .... don't hate me. You know who you are. )
But this? This anime is one of the few I could watch over and over again. It has almost everything a person could want from a series.
The concepts of loyalty, "how far would you go for someone you love," honor, friendship, family ( and the question: who is your real family? Those you share blood with, or those you spill blood with? ), and sacrifice are constantly an underlying theme to all the politics, manipulation, and action scenes.
The main character is disgustingly strong -- both because of his intelligence and an acquired ability. Yet he still loses, and he loses hard. There are some truly gut-wrenching moments throughout the course of season one and two.
For those interested: Watch the anime first. The manga are more of a " What if ... " scenario.