Rinrin

As the mechanical prodigy of the sisters, this character is constantly engaged in creating intricate inventions, ranging from communication devices to submarines and even robot replicas. She partners with Yotsuba in the Sister Princess Repure arc to investigate secrets about their brother, showcasing her exceptional mechanical talent. Driven by a desire to bring happiness to her brother, her dedication to her inventive work is deeply heartfelt, often finding joy in the support she receives from him.