Usonoir is a male antagonist from the anime Star Detective Precure!. His character is primarily defined by his role as a commanding figure within the series' antagonistic forces, and he appears to be an adult character. Specific physical traits such as eye color, hair color, and hair length are not documented, and he is noted as being an "In Armor" character type, meaning his design likely features a suit of armor that obscures many of his visual characteristics.

Usonoir functions as a leader or high-ranking authority among the villains. His primary role in the story involves directing the actions of lower-ranking antagonists to achieve the group's goals. In this capacity, he has been shown giving orders to his subordinate Nijee, specifically tasking him with the mission of stealing Makoto Jewels, which are important items within the series. Usonoir is depicted as a stern and demanding superior who has little tolerance for failure. He closely monitors the performance of his subordinates, and it is documented that he noticed Nijee's repeated failures. He made it clear that if Nijee were to fail again, he would not be offered another chance, demonstrating a ruthless and pragmatic approach to leadership.

Usonoir also observes the battles between his forces and the main heroines, the Precure. He has been shown watching these confrontations from what appears to be a theater, alongside other characters such as Luluka and Mashutan. His attention to these events suggests a vested interest in the outcome of the conflict and the effectiveness of his agents. Information regarding his deeper personal motivations, his background or origins, any significant character development he undergoes throughout the series, and any notable abilities he possesses for combat or other purposes is absent. Key relationships are only established with his subordinates, as there is no available information on connections to other characters beyond this dynamic.