Blade of the Immortal by Hiroaki Samura will keep you on the edge of your seat. In feudal Japan, Manji is a cursed ronin warrior who cannot die. To end his endless suffering, he must kill 1000 evil men. His mission begins when he is asked to help a young girl avenge her parents' murderers, and it won't end until he has spilled the blood of a thousand.
Note: The tankoubon release includes 207 chapters in 30 volumes, while the Dark Horse release consists of 208 chapters in 31 volumes. The magazine release, which includes a prologue, has 219 chapters.