Rinrin (sometimes stylized RinRin) is a mechanical genius. . She is usually asking Wataru for a research grant for her research. Rinrin is usually building something frequently her Mecha-Rinrin Because she looks a lot like Mamoru she and her are confused for each other.
She speaks with a strong Chinese accent and addresses her brother as Aniki (アニキ?), another way for a boy to address his brother. In English, she calls him "Bro"
Her birthday is July 9, is a Cancer and measures 152 cm (about 5') in height.
Rinrin is devoted to her research and is always seen with a device she has built or asking Wataru for research fund.