Fubuki Momose is a slim, pale high school student standing 158 cm tall, with notable measurements of 85 cm (bust), 55 cm (waist), and 84 cm (hips). She has long brown hair tied in a waist-length ponytail with spiky bangs, typically secured with a ribbon hair tie, and distinctive violet tsurime eyes. Her usual attire includes her school uniform, a sports uniform with bloomers, or a jacket.

A popular student known for honorable traits, Fubuki plays volleyball in a school sports club. She shares a long-standing childhood friendship with Shinichi Kawahara, whom she exclusively likes romantically. Another student, Takaaki Tsumura, harbors unreciprocated feelings for her.

Following an earthquake that collapses the school building, Fubuki becomes one of four survivors, alongside Shinichi, Takaaki, and a junior female student. Confined in the rubble, Fubuki confesses her feelings to Shinichi, who reciprocates. Takaaki manipulates the situation by falsely accusing Shinichi of sexual interest in the junior girl – who does like Shinichi – creating doubt between the childhood friends. Exploiting this manufactured distrust and the isolated environment, Takaaki sexually assaults the junior girl and later targets Fubuki. These violations occur while Shinichi remains unaware and confused. Takaaki exploits Fubuki's emotional attachment to Shinichi and the traumatic environment to manipulate her.