This wallpaper comes from a series called C.A.T. (Confindential Assassination Troop) by Fung Chin Pang. The main character is a girl often called Cat, an assassin for hire with a dark past. Other characters include a Chinese assassin with an experties for knives, a Russian assassination group that was technially on death row, and an estranged and dying genius who started the entire thing.
You can read the series on MangaFox.
C.A.T. belongs to Fung Chin Pang, the wallpaper was made by me.