Remember about K anime that I told you before? This anime is also have a manga called K -Memory of Red-, illustrated by Kuroe Yui
In this manga, we can meet another chara from the anime although the protagonist is different and this manga is also really cool like the anime ^^
Apperently this story is about organization called Homra. This organization is build by a red king with demon ability and if you can join into Homra, you can gain extraordinary powers.
You can read this manga in here K manga