In the Hagakure, a book written by the samurai official Yamamoto Tsunetomo in the 17th-century, the author writes about the different characteristics of people that make up society. He points out that the most valuable person is the “kusemono.”
Translators of the Hagakure point out that the modern meaning of that term is that of a “ruffian” or an eccentric. So why was the kusemono so valuable? According to the Hagakure, a kusemono is a person who avoids trouble, keeps to themselves, and only appears when needed. Not unlike the solitary hero of samurai movies in the 1960’s, a kusemono eschews high honors and recognition and prefers to keep to their own devices until duty calls. Then, when the job is completed, they return to their solitary ways.
In short, a kusemono is like a friend.