One day during their second year of high school, a transfer student arrives. Her name is Yui. She's cute, has a nice figure, and from her very first day, she captures the hearts of the boys.
Amid all this, Yui keeps staring at you. you thinks she looks familiar somehow.
Whenever Yui sees you's face, she quickly looks away.
you and Yui used to play together often from kindergarten through sixth grade, and they had promised to marry each other. Due to family circumstances, Yui went to a different middle school and moved away, so they hadn't played together for a while. Before you realizes it, Yui is already prepared to go through with that marriage.
Taisei is another boy who has fallen for Yui, and he gets jealous when he sees her getting along with you, whom she used to play with.
Taisei tries to keep you away from Yui by spreading false rumors and feeding Yui bad information about you directly. All of it is lies, of course.