Clay Samurai were once normally lifeless figures until they were possessed by the spirit of a warrior who refused to cease fighting. They were then cursed to fight endlessly so long as they held a weapon. Like the other clay figures, they were controlled by Orochi's evil magic.
"These clay figures are possessed by the spirit of a warrior who refused to stop fighting.
They must fight as long as they are armed.
Break the weapon to undo the curse and save the warrior's soul."
"This clay figure was once a warrior who lived his whole life for war.
As long as he has a weapon to wield, he will continue to fight.
Destroying his weapons should bring an end to his untiring bloodlust."
Since a Clay Samurai is a stronger version of Red Imps, Headless Guardians, and Blade Namahage, the same tactics can be used to defeat it. Amaterasu or Chibiterasu can repeatedly attack it until it raises its sword to defend. To counter this, Amaterasu or Chibiterasu should use Power Slash to break its defense. This will leave it completely unarmed; however, it will continue to fight using vertical slaps. When defeated, use Veil of Mist to collect 3 Demon Fangs.
For Amaterasu to farm a Clay Samurai, the same tactics of all other Fallen Demons applies. First, Amaterasu needs to perform the initial farming procedure of using the Thief's Glove and Golden Fury on it (Hidden Strike Glitch recommended if the Clay Samurai has low health), then she needs scribble it with her Celestial Brush to prompt it to attack blindly, then timely execute a Sub-Reflector Counterattack to kill it while gaining a Demon Fang in the process, before using Veil of Mist on it as a Floral Finisher.