In the winter of his second year of high school, Yuuichi was forced to become hospitalised due to hepatitis. Since his symptoms were not severe, he would attempt to escape from the hospital in the middle of the night, but would be scolded by the nurse Akiko.

One day, a girl is transferred in from another hospital. Akiko asks Yuuichi to keep the girl company, since even she herself is at a loss for how to handle the girl. Timidly, Yuuichi enters the girl's room. There, he sees Rika, a beautiful young girl with long black hair.