Rina is a female-form android initially created as a bodyguard for an unidentified VIP. Illegal modifications added sexual functions, preventing her from returning to the manufacturer without exposing her former master. During an assassination attempt targeting that master, she sustained damage to her right leg, causing periodic malfunctions. Her master subsequently abandoned her, leaving her ownerless and technically a fugitive.

Within the café setting, Rina passes as human while concealing her android identity and leg issues. She forms a romantic relationship with Koji, another patron she believes is human. Despite an outwardly confident appearance, she displays reserved and shy behavior in interactions. Rina remains unaware of Koji's existing relationship with his mistress and experiences deep disappointment upon discovering his deception.

Her fear of exposure stems from the belief that Koji would reject her if he learned she is an android. This mirrors Koji's own concealment of his nature, creating mutual uncertainty about their identities.