Kubikiri Asa (Samurai Executioner) - Koike, Kazuo Kojima, Goseki

In a prison world, there are few good stories, and this is the world of Kubikiri Asa, the beheader and master samurai under the Shogun. It's a world full of vengeance, greed, and violence. A world of depravity and sin. One man can set things straight if he can keep his wits. This is a story of extreme proportions, of sword study thick in tradition and with grim purpose, of blood rivers, agonizing screams, bondage, torture, and the evil prevalent in human failure. Drafted by the confirmed masters of the international medium of manga, Samurai Executioner is a shocking combination of darkness and fire, fine lines, and a fine man in the face of human decline.

(Source: Dark Horse)

Kubikiri Asawas first published in English as Samurai Executioner by Dark Horse from July 28, 2004 to May 31, 2006, with the digital edition released May 18, 2011 to May 9, 2012. The series was re-published in omnibus format, with four volumes, by the same publisher, from May 14, 2014 to February 11, 2015.