This refers to The Man in the High Castle S3/Ep9 "Baku".
When Kido takes Frank to his place of execution, he chooses a location--a former Japanese internment camp--where Frank's symbol has been painted on a rock. Kido bows to Frank, a sign of respect. Kido shows him further honor by changing into his uniform to perform the execution, a recognition of the formality, and executes him in an honorable way, by a clean beheading with a single stroke of the sword. (Compare to the execution of the traitor Nakamura. In seppuku, ritual suicide, kaishaku is a beheading at the moment of greatest agony, to preserve the honor of the dying samurai.)
Why does Kido pay such honors to Frank?
The Japanese term Baku refers to "supernatural beings that are said to devour dreams and nightmares."