Kasumi Yuma

Younger of the twin sisters. A carefree and talkative hyperactive girl. The twins never leave each other's side, with Yuma looking after her older sister. They go swimming almost every day, so she got tanned a bit. She's a great fan of an anime called Doricchu, so to look like the main character of the show, she wears a tail and sets her hair ribbon in the form of cat ears.
Calls the protagonist "Onii-sama".