Guzuko emerged as a black LRIG forged directly from the memories of her Selector, Sou Sumida. Her personality was defined by extreme timidity, frequently expressed through apologetic phrases like "I'm sorry" or "Excuse me" – behaviors instilled by Sou's persistent verbal abuse throughout their partnership. Despite this submissive demeanor, she occasionally mustered the courage to scold Sou when he committed acts she deemed morally wrong, such as bullying weaker opponents during Selector battles. This dynamic persisted until Sou lost his final memory coin, triggering Guzuko's takeover of his physical body. Following this transition, she entered the service of Kou Satomi, acting as his errand girl and tasked with observing and documenting other Selectors' interactions for his entertainment.

Guzuko later transitioned into an antagonistic role, aligning herself with the primary antagonist Carnival, who controlled multiple LRIGs. Operating under Carnival's influence, she participated in activities opposing the protagonists. However, during the decisive confrontation, Guzuko and fellow LRIG Aya reconsidered their loyalties upon realizing the protagonists' success could restore their former Selectors. This led them to defect from Carnival and assist the protagonists in defeating her, shifting from antagonist to ally.

Following the conflict's resolution and the permanent end to Selector battles, the restoration process returned Guzuko to human form, aligning with the broader restoration of affected individuals where LRIGs gained human existence. Physically, she was characterized by maroon shoulder-length hair, pink eyes, and attire consisting of a black dress with red gloves. Her core relationships centered on the abusive dynamic with Sou Sumida, enduring mistreatment without overt hatred, and her subservient role under Kou Satomi after assuming Sou's body.