High school student Yosuke spends most of his free time sitting near a floodgate and playing the same short tune on his acoustic guitar. He is often joined by a girl in his class, Yu. Yu hums Yosuke's tune to her older sister, who is mourning her deceased boyfriend. Yu sets up a few meetings between Yosuke and her sister. While talking with Yosuke after school, Yu kisses him, but Yosuke walks away, leaving Yu devastated. While walking to see Yosuke, Yu's sister is hit by a truck and enters a coma. Yu tells Yosuke that she wants to hear his song when he finishes it.
