In the high school days of Mio Miyamasu and Arata Kishimo, who have been close friends since they were children, Mio harbors unspoken feelings for Arata. Despite this, she lacks the courage to tell him. Her friend Madoka queries Mio about her feelings towards Arata, to which Mio reluctantly admits nothing and instead urges Madoka to express her own feelings for Arata.
One day, while visiting a fortune-teller, Arata senses something amiss and attempts to quickly exit the establishment, irritating Mio in the process. This encounter leads Mio to reconsider her connection with Arata, culminating in a heated argument. Later that evening, filled with regret over their quarrel, Mio decides to go out in the rain to apologize and confess her true emotions to Arata. However, an unexpected incident on her journey alters Mio's life dramatically.