Izumi Shinohara is an 18-year-old twelfth-grade student and classmate of protagonist Ryunosuke. Standing 150 cm tall with a slim build, she has pale skin, medium breasts, short black hair featuring spiky bangs, and blue tareme-shaped eyes. Born into wealth, her tomboy personality manifests through masculine speech patterns while using "watashi" for self-reference.

She actively participates in her school's kyudo club and enjoys skiing. Her distinctive wardrobe blends traditional Japanese attire—hakama, haori, and yukata—with modern pieces like beanies, scarves, school uniforms, formal shirts (accessorized with bow ties or neckties), trousers, vests, jackets, coats, and a frequently carried bag.

Izumi shares a close friendship with Tomomi Mizuno, another classmate and Ryunosuke's childhood friend. A key narrative constraint prevents Ryunosuke from pursuing romantic relationships with both Izumi and Tomomi simultaneously, creating a mutually exclusive choice. This positions Izumi as a potential romantic interest during the winter vacation preceding graduation, where Ryunosuke must develop a relationship with one eligible character.