Final answer:
A casting director is the collaborator who handles the casting process for a film, focusing on finding actors that match the director's vision and setting up auditions, while the director retains the final artistic choice.
Step-by-step explanation:
The collaborator most likely to handle the casting process for Yukari is a casting director. The casting director's role is to sift through the many actors and present a manageable group of candidates to the director. They work closely with talent agencies and are very knowledgeable about the acting scene, particularly in competitive markets like New York. The casting director helps in finding actors that match the director's vision based on the character breakdowns and is responsible for setting up auditions.
While the director is the one who makes the final artistic choice about who is in the cast, the economic negotiations are handled by the producer. Moreover, unlike the assistant director, stage manager, or editor, the casting director focuses specifically on the pre-production phase of finding talent, leaving technicalities, rehearsals, and post-production work to others.