Riku is a tomboy. She doesn't trust the others and always worries for her twin Risa. She always make her best for her and usually helps her with homeworks and similar, since she's very good at them. She's very skilled in sports and she's very proud. In fact, at the begin of her love story with Niwa Daisuke, she pretends she's not in love with him. After an accident that happen in a school trip, she falls in love with him and it is the same for Daisuke, who previously loved her twin Risa. Since she doesn't want to admit her feelings, she sees that Risa is in love with him and starts to cheer her up, suffering very much inside of her. She has always been complexed because of the expansive personality of Risa, but she will approache to Daisuke and when he will give her as a present a white ribbon for the White Day, it would be the symbol of their love: their relationship as lovers was starting. She's an opened book, in fact when there's something, it is very simply to understand her opinion. As Risa, she's very clumsy, but she always tries to do her best for everything she does.