Riri, designated the First Person, originated as an orphan after her parents perished from overwork. The original Wakaba discovered and revived her, but she declined to return to Earth, opting to remain alongside him. Witnessing Wakaba's exhaustive labor with Kemurikusa, she engineered a red variant intended to eradicate all other Kemurikusa and liberate him. This plan collapsed when the red Kemurikusa grew uncontrollable.

One week after Wakaba left to confront the red Kemurikusa threat, Riri transformed herself into Kemurikusa to aid him. During metamorphosis, she learned of Wakaba's death but could not reverse the process. As she converted, she fragmented into multiple entities—the future sisters. To shield them from her mission to save Wakaba, she erased their collective memories, granting them autonomy.

Riri held extensive knowledge of Kemurikusa, enabling her to blend types for new colors and effects. She cherished insects and deliberately mispronounced "Nushi" (hostile robots) as "Mushi." Her demeanor remained cheerful and caring, reflecting her devotion to Wakaba’s well-being.

Her legacy persisted through the sisters, each name incorporating "Ri" (Rin, Ritsu, Rina, Riku, Ryo, Ryoku) as tribute. Rin inherited balance and physical strength, Ritsu hearing, and Rina taste. Their journey ultimately fulfilled Riri’s unspoken wish for their happiness, culminating in their arrival at a water-rich paradise beyond the red fog. Riri’s actions defined the sisters’ origins, abilities, and shared purpose.