Oguma serves as the adoptive father of Louis and former owner of the Horns Conglomerate. He is a middle-aged red deer distinguished by his curling antlers and standard square-framed glasses. He consistently appears in professional attire: an emerald green suit, cedar brown collared shirt, dark gray tie, and brown shoes.

His personality remains enigmatic but manifests through interactions with Louis, expressing pride or disappointment by purchasing expensive items—such as a 500,000-yen bicycle after Louis failed to achieve a perfect test score. Privately sterile, this condition motivated Oguma to adopt Louis from the Black Market for ¥7,000,000, explicitly intending to groom him as his corporate successor.

For security, Oguma kept a taser prod in his residence. He notably used it to investigate a scream from Louis's room, though the incident proved a false alarm caused by Louis's leg pain. His family connections include being the father-in-law of Azuki, Louis's arranged fiancée, after forging a business-oriented marriage alliance with Azuki's father.

Trivia notes his name derives from the Gaelic god of speech and learning, coincidentally linking to Louis's later perception of him and the lion Ibuki as paternal figures—both wearing glasses. The name "Oguma" (小熊) also translates to "small bear" and alternatively references an area in Fukushima Prefecture.