Oscar is Inspector Zenigata's second in command and Lieutenant in the spin-off series, "The Woman Called Fujiko Mine".
Oscar is a young man with a somewhat feminine appearance. He has long curly brown hair and wears a coat possibly based on a naval commander's uniform with brass buttons at the sleeves, torso, and collar.
His body is slightly hourglass shaped, making it easy for him to disguise himself as a woman.
It is revealed as early on as the first episode in the Fujiko Mine series that Oscar has deep affections for his superior and adopted father, Zenigata. However, it is hinted at that he is only lustful towards Zenigata rather than men as a whole.
Oscar is shown to be extremely loyal to the Inspector. He is willing to do whatever it takes to impress Zenigata and eventually resorts to illegal means in order to gain the Inspector's acceptance and affection. He listens to the Inspector speak with eagerness and always seems to be extremely impressed by his investigative skills.
Oscar is also shown to be very stubborn. When he was a child, he risked being beaten for the sake of a single franc.
Not much is known about Oscar's past other than the fact that he was born in Paris, France.
Oscar very likely was a homeless orphan as he was seen in a flashback fight a group of boys for a single franc. Oscar was badly beaten and eventually jumped off the Alexander Bridge while escaping his bullies. Zenigata happened to be standing by the river and saw Oscar jump. He quickly fished him out of the river and possibly adopted him afterwards.