Suzu Sakuma (佐久間 すず Sakuma Suzu) is Satoshi's younger cousin who is a well-known teen model who loves beautiful things. After seeing Yuu's picture, she fell in love with his looks and requested that he be included in a cosmetics commercial that she was shooting. Afterwards, she asked Satoshi to arrange for Yuu to become her math tutor. Feeling that Miki is too plain for Yuu, then believing that Miki is cheating with Kei and that Meiko loves Yuu, Suzu tries to break up Yuu and Miki's relationship. When her efforts cause Miki and Yuu to fight, she feels bad and apologizes. She later meets and begins following Kei, after seeing him play the piano. She admires him and they fall in love. They date for 13 years and put off getting married as Kei’s band becomes internationally famous. After much talk between them, they decide to get married and later have a baby girl named Rion.
In the anime adaptation, Suzu is shown to be in love with Yuu herself, rather than wanting to have him date Miki. In the anime television series, Suzu Sakuma is voiced by Sakura Tange in Japanese and Mia Bradley in English.