Risa Harada (原田梨紗)
Background
There is an ongoing sisterly rivalry between her and Riku. Compared to her sister she seems more innocent and clumsier and can be seen as your typical "girly-girl" though shows the same stubbornness, tenacity, and kindness as Riku. She would much rather prefer fashion and relationships than to physical activities. In terms of physical features her hair is much longer and she has a "softer voice," apart from that the two can't be distinguished (shown in episode 5 of the anime when the two switch places so Risa can get out of chopping cabbage as a form of after school punishment).
As the series progresses, Risa breaks out of being a naive little girl and develops into a more mature young lady.