Hotaru Shirakawa is a third-year student at Hamasaki High School who carries herself with a childish and often immature demeanor, occasionally acting like an airhead. Her favorite pastime is playing the piano.

She has long brown hair, typically styled in twin tails that fall to her hips, and brown eyes. Standing 158 cm tall with measurements of 80-58-86 cm, her usual outfit is her school uniform, complete with a miniskirt, a ribbon hair tie, thigh-high stockings, and loafers.

Her closest friend is Tomoe Tobise, another third-year at Hamasaki High. Hotaru is in a relationship with Ken Inami, having confessed her feelings to him at Christmas. Though they are together, she worries about the consistency of his affection for her, a concern that grows when he becomes involved with Tomoe, suggesting a potential love triangle.

Hotaru has an older sister, Shizuru Shirakawa, a university student in her third year. Shizuru is adept at making desserts, which Hotaru enjoys, and has a tendency to spoil and look after her younger sister, frequently assisting her with troubles related to Ken.

Beyond the main story of *Memories Off 2nd*, Hotaru appears in other official media. She features in both stories of the *Memories Off 3.5* animated adaptation. She also appears as a secondary character in *Memories Off ~Sorekara~*, where she aids another character, Inori, with her feelings for Isshu.

A special edition animated release, *Memories Off 2nd Special Edition ~Nocturne~*, follows the same storyline as the original but with a stronger focus on her perspective, incorporating new footage centered around her.