People Transformed Into Demon What Is This Anime? I've Been Searching And Searching.?

What is this anime? I've been searching and searching.? - people transformed into demon

I saw this cartoon a while ago, not much (in that) I only know that the show with this man, who had been wounded and killed on a mission to all those demons started. He was a man of strong sword with a long sword. And then back to his childhood when he and then (a few were really knows with the boys in blue and white) have become firm friends. If he came into his group. There was a girl in love with the pale guy. Perhaps he was black ...? Really nice, but ultimately fell in love with a swordsman, though he initially hated.

At the end .... The Dude pale bind these demons to kill and end all of his friends and the people in another sword. Always against the child: (It is curious that demon in the end.

: (Help?