Minoru Ōkuma (also romanized Minoru Ohkuma, Okuma, or Ookuma) is a first-year student in Class 1-3 at Roubai Girls' Academy, assigned seat number three. Her surname means "big bear," while her given name translates to "fruit," "good result," or "truth." She has dark brown hair and brown eyes, with a birthday on November 24th, making her zodiac sign Sagittarius.

She resides in the school dormitory, sharing a room with Ayumi Tougeguchi. Minoru possesses an inquisitive and nature-oriented personality, showing a strong preference for rational phenomena and living organisms. She avoids direct social interaction, focusing instead on observing people and wildlife. She meticulously records unique characteristics, sketches her observations, and documents contextual details like discovery circumstances in detailed notebooks, a practice that has improved her artistic abilities over time. Minoru believes noting others' preferences aids future conversations, though her detached observation style—eliminating her own presence to achieve objectivity—may resemble espionage. Komichi Akebi is her primary focus of interest, designated "spy target number one" since their first encounter.

Minoru exhibits fearlessness toward nature, handling snakes without hesitation. She developed an interest in the small roads surrounding Roubai Academy after enrolling. During school events like the sports festival, she participated in table tennis with Tougeguchi and joined a swimming relay team alongside Komichi, Ai Tatsumori, and Riri Minakami, contributing to their first-place finish. Her activities reflect a gradual increase in social engagement despite her initial preference for observation.