Rinrin
Rinrin is the mechanical genius of the sisters and is always hard at work with her inventions. Early on, one of her creations that we meet is Mecha-Rinrin, a giant robot that usually accompanies her. She definitely has a talent for machines and anything mechanical as she makes messenger phones, a submarine, and is even in the process of creating a robot replica of herself. In Sister Princess Repure, she teams up with Yotsuba to form a detective duo to find out details about their big brother that they don't know. Unfortunately, this takes away from really showing her amazing skills as an inventor that are prominent throughout the first Sister Princess anime series and in the original stories. Like all of her sisters, she really puts her heart into her work, as she wants her brother to be happy. And of course, any help and encouragement that her brother Wataru can give her always puts a smile on her face.