Suzu is Daichi's ex-girlfriend. They've been dating for three and a half years. Yamato said that they're in love with each other and he wants to marry her.

Say "I Love You"
The story of first love centers around Mei Tachibana, a girl who has never made friends or had a boyfriend in 16 years. One day, she accidentally injures Yamato Kurosawa, the school's most popular boy. For some reason, Yamato becomes interested in Mei and starts a one-sided friendship with her. He even protects her from a stalker — by kissing her.