I'm surprised no one mentions these two solid series
Kurozuka
Blade of the ImmortalThe series begins in 12th century Japan and centers on Kuro, a character based loosely on the legendary Japanese swordsman Minamoto no Yoshitsune. Kuro and his servant, Benkei, meet a beautiful and mysterious woman named Kuromitsu while on the run from Kuro's elder brother, who seeks his life. Kuromitsu and Kuro fall in love, but he soon discovers that she harbors a terrible secret: she is a vampiric immortal. Following an attack by his pursuers, Kuro is badly injured and must imbibe Kuromitsu's blood in order to save his own life. Kuro is then betrayed and attacked by Benkei, who has been subverted by a shadowy organization called the Red Army, and Kuro's head is severed, which interferes with his transformation into a fully immortal being.
"To end his eternal suffering, he must slay one thousand enemies!" Manji, a ronin warrior of feudal Japan, has been cursed with immortality. To rid himself of this curse and end his life of misery, he must slay one thousand evil men! His quest begins when a young girl seeks his help in taking revenge on her parents' killers... and his quest won't end until the blood of a thousand has spilled!
XI Wiki


But the speed at which episodes come out is slooow... Actually wasn't the last one released like 2 years ago?
