Keita Oguma is a second-year student at Soran High School and a member of the school's rugby team. He possesses shaggy brown hair and maintains a consistently calm, welcoming demeanor, his expression perpetually pleasant. Valuing comfort, he frequently layers a tan sweater over his standard school uniform of a white shirt, red tie, trousers, and dress shoes, forgoing the blue blazer.

His personality radiates extreme gentleness, kindness, and cheerfulness. This inherent kindness creates a significant challenge to his effectiveness on the rugby field, even though his notable physical strength is recognized as top-tier among his teammates. He struggles to reconcile his gentle nature with the sport's demands for aggression, a conflict between his formidable capabilities and his personality that impedes his potential during play. Deeply caring about those around him, he leads others with a smile, positively contributing to team morale.

His given name, Keita (景太), combines "scenery, view" (景) and "thick, big, great" (太). His surname, Oguma (小熊), translates to "small" (小) and "bear" (熊).