This. Is. One. Of. The. Best. Anime. EVER!!!
There's something here for everyone: epic sword fights, strategic battle techniques, well- developed chararacters, humour and a few mysteries to bind it all together. The voice actors all fit their characters perfectly (some may recognize Daisuke Ono, the voice of Saizou, as Sebastian from Kuroshitsuji), and the characters themselves are creative and often have more than one side to their personalities.
I've watched and read a lot of shounen anime, but this one definitely shines and stands out from the rest. I highly recommend it.