Like Chiori, Riu was also born in Tokyo. Her father and Chiori's father are good friends. Because Chiori's parents are away from home most of the time, Riu has been living with Chiori and taking care of her like an elder sister ever since they were children. She also started playing Mahjong because of Chiori. Over time, Kujou fell in love with the game. Her hobby is to collect all kinds of beautiful dresses.
