Himari Ashihara has always attended all-girls schools. Because of this, she has virtually no experience with men and thus is unable to understand or deal with them at all. Her friends, Shuuko Tokiwa and Yae Kashino, decide the best way for her to overcome her problem is to confess to someone.
Gathering her courage, Himari asks Kai Satoru, a boy she crosses paths with while walking to school, out on a date by the river. To her shock, Kai accepts. Unsure and taken aback, Himari makes a deal with her friends: if he shows up at the riverbank, she will continue dating him—and if he is not there, she is allowed to apologize and say she has mistaken him for another person. Anxiously waiting at their meeting place, she is surprised when Kai makes an appearance, marking the beginning of Himari's first ever relationship.