SWORD OF THE STRANGER

Sword of the Stranger summary:

Hunted by the Mings from China, young Kotaro and his dog meet Nanashi, a samurai who is constantly being haunted by dreams of the past which lead him to seal his sword. Among the Mings is a fiercesome Western fighter named Rarou, who desires only 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.
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Based on the anime film of the same name.