Ghost Dog: Even if one's head were to be suddenly cut off, he should be able to do one more action with certainty. With martial valor, if one becomes like a revengeful ghost and shows great determination, though his head is cut off, he should not die.
Ghost Dog: If one were to say in a word what the condition of being a samurai is, its basis lies first in seriously devoting one's body and soul to his master.
Answer: Ghost Dog eliminated virtually everyone and was just finishing business. Louie was the only mobster left, but he was sworn to protect and obey him after he was saved by Louie as a young man. He owed it to Louie to finish the job.
Erik M.