Oscar serves as the Guardian of Fire in the Shinchou Universe (Sacred Bird Cosmos). He is a tall, muscular man with red hair and blue eyes, typically seen wearing armor. His personality blends flirtatiousness and chivalry, often exhibiting a protective and somewhat chauvinistic attitude toward women.

Prior to the main series, Oscar developed a romantic relationship with Angelique Limoges during her time as a Queen Candidate. This relationship ended upon her ascension as the 256th Queen, as her cosmic duties superseded personal attachments. Later interactions show no residual romantic tension, indicating both moved forward professionally.

During Ange's mission as the Legendary Étoile, Oscar acts as her mentor. He initially teases her about insecurities but grows to respect her determination and kindness. His support includes accompanying Ange to festivals, encouraging her to embrace her role, and advising her during crises. When imbalances in Sacrea energy threaten development, he collaborates with other Guardians to stabilize the cosmos.

In subsequent missions, Oscar helps pacify rogue Sacrea Spirits and assists Ange in recruiting new Guardians for the Sacred Beast Cosmos. He demonstrates tactical leadership during confrontations, especially against the Spirit of Sacrea. His protective instincts emerge when advising Ange about the burdens of Guardianship, reflecting his understanding of their sacrifices.

Later portrayals maintain Oscar's flirtatious demeanor while showing increased emotional openness. He joins fellow Guardians in preparing a farewell gathering for Ange and Rachel, indicating camaraderie. In his romantic route within later game narratives, a confession scene includes two kisses, showing his willingness to commit emotionally despite his typically lighthearted approach to relationships.