Sawako, a clumsy and endearing high school girl, has been pining for her classmate, Kazehara, for quite some time. After mustering up the courage, she decides to confess her feelings to him using a rubber band (or "gomu" in Japanese) as a prop. The plan involves writing her confession on a piece of paper, attaching it to a rubber band, and then shooting it at Kazehara using a makeshift catapult. However, things don't go as smoothly as she had hoped, and her confession ends up being a comedic fiasco.
To understand why this mistake is so easy (and so devastating), we need to look at Japanese vocabulary networks. gomu o tsukete to iimashita yo