Rin Itoshi's tragic backstory plays a significant role in shaping his behavior and goals throughout the story. His past experiences of loss, betrayal, or hardship may have led him to develop certain defense mechanisms, such as being guarded or closed off emotionally. These experiences could have also motivated him to pursue specific goals or ambitions, perhaps driven by a desire for revenge, justice, or redemption. Ultimately, Rin Itoshi's backstory likely serves as a powerful motivator and a key factor in understanding his actions and decisions in the present.