Sword of the Stranger (ストレンヂア 無皇刃譚, Sutorenja Mukouhadan?) (Stranger Mukou Hadan) is a Japanese animated feature film directed by Masahiro Andō and produced by BONES studios. The film follows a swordsman with no name and a golden-haired assassin as circumstances draw them towards a mysterious young boy.

Hunted by the Mings from China, young Kotaro and his dog meet a nameless samurai ("Nanashi") who is haunted constantly by ghosts from his past which has lead him to avoid drawing his sword ever again

Among the Mings is a fiercesome Western fighter named Rarou, whose only desire is to find a worthy opponent. When both groups clash with a Sengoku-era feudal lord, a proud general, and monks torn between faith and survival, the reason behind the Mings' pursuit tests the bond between Kotaro and Nanashi.

Source: Wikipedia