Rin Kusakabe is a Burst Linker affiliated with the Great Wall legion. She shares a unique connection with the duel avatar Ash Roller, ceding control to this entity during battles. Ash Roller refers to Rin as his "younger sister," though the exact nature of their relationship is undefined—potentially a copy of her brother, a split personality, or another manifestation based on his consciousness. Despite sharing the avatar, Rin and Ash Roller cannot directly communicate, though each observes the other's actions.

Characterized by extreme shyness and low self-esteem mirroring Haruyuki Arita's own struggles, Rin exhibits clumsiness in daily life. This is notably demonstrated when she broke over ten plates and glasses while working in a hospital cafeteria during summer. Her background centers on her older brother, Rinta Kusakabe, a motorcycle racer who lent her his Neurolinker before sustaining injuries in an accident that left him comatose. To visit him frequently, Rin enrolled in a school in Shibuya and took a job at his hospital's cafeteria. There, she accidentally spilled water on Kurasaki Fūko, who subsequently gifted her Brain Burst. Rin continues to use Rinta's Neurolinker for acceleration.

Physically, Rin stands slightly taller than Haruyuki Arita, with brown-grayish hair and purple eyes. Her standard network avatar wears a studded leather jacket and ripped jeans. An alternate design in *Accel World VS Sword Art Online: Millennium Twilight* depicts her as a human-sheep hybrid featuring horns and a red neck belt.

Rin develops romantic feelings for Haruyuki Arita, creating interpersonal tension within her social circle. Her family resides in Egota, Nakano, and she commutes to a private school in Shibuya. She made cameo appearances in Episode 24 and the OVA *Vacation*. In *Accel World: Infinite Burst*, no concrete details about her role or development are provided in the available sources.