The anime will follow the adventures of Baron, a man living on continent of Arad in the year 981 after "the cursed light of Kazan" has fallen across the land. Thanks to the curse, one of his arms has become possessed. After finding a sword that has been possessed by the spirit Roxy, he embarks on a quest to unravel the secret of the curse and meets various people who also join his party.—AniDB

On the continent of Arad in the year 981, a man named Barn has one of his arms possessed by the "cursed light of Kazan" which spread across the land. After finding a sword which is possessed by the spirit Roxy, he becomes a Demon Swordsman and embarks on a quest to unravel the secret of the curse and meets various people who also join his party.—SIGN IN REGISTER Arad Senki Wiki

Swordsman Baron travels the world of Arad to find a way to heal his demonic left arm. Accompanying him is Roxy, the ghost of a woman who unwillingly unleashed the evil that also caused Barons transformation. On their travel they get to know other fighters who accompany them and soon they call their group the "Party".—Anime News Network

Thirteen years ago, the demon Kazan placed a curse on the continent of Arad, causing legions of demons to sprout from the earth. One young man named Baron also suffered its effects and is cursed with a demonic left arm. Baron now travels the land with Roxy, the spirit who resides in his sword, in the hopes of finding a cure. They are soon joined by self-proclaimed 'Gunner of Love' Capensis who literally falls from the sky; freakishly strong fist-fighter Ryunmei; and troublesome young mage Ixia. As they traverse a world of underground fight clubs and axe-wielding demons, will the party be able to find a way to remove the jinx on Baron's arm, not to mention survive Ixia's attempts at using magic?—Anime-Planet