Rinia is an early prototype android combat maid manufactured by AC Company, a kind-hearted yet mechanically inefficient model suffering from complete memory loss. She arrives at Moekko Island for communication and operational training under Takahiro Kanzaki, the island's owner. Takahiro initially views her as incompetent due to her tendency to cause accidents during routine tasks. Despite her clumsiness and outdated systems, Rinia persistently strives to prove her worth through earnest efforts in domestic duties like cleaning and cooking.

Her physical design features two functional pairs of arms, with an additional set extending from her hair. These appendages perform basic tasks such as opening doors or lifting objects but do not significantly enhance her capabilities beyond standard android functions. The memory loss afflicting both Rinia and Takahiro forms a narrative link; fragmentary flashbacks hint at a potential shared history preceding their current circumstances, though the exact cause remains undisclosed.

Across her story arc, Rinia gradually influences Takahiro's emotional state, transforming his initial resentment into protective concern through her unwavering dedication and positive attitude. This development culminates when she prevents his expulsion from the island by demonstrating her value to their superiors. Her route in the original visual novel emphasizes non-romantic bonding through daily coexistence, focusing on mutual reliance during crises and concluding with an affirmation of her place within the island's community.

In expanded media, including the OVA adaptation and light novels, Rinia retains her core traits of diligence and naiveté. Her interactions primarily drive comedic mishaps and mild drama. She faces external threats such as corporate assassination attempts against Takahiro; during these, her combat programming activates defensively despite her primary role as a domestic maid.