Yuichi Eizaki (voiced by Kenichi Suzumura) is an ordinary 17-year-old boy. In his 17-year long life, nothing special worth recording happened. However, in this year, Yuichi was hospitalized because of hepatitis A. In the hospital, Yuichi met the tough nurse Akiko Tanizaki (voiced by Yuki Kodaira) and the serious and responsible Natsume Goro (voiced by Hiroaki Hirata). In addition, Yuichi also met the girl who changed his life. The girl's name is Rika Akiba (voiced by Mikako Takahashi). She suffers from congenital heart valve insufficiency and is a "resident population" in the hospital. Rika is full of curiosity about the strange world outside, and Yuichi's arrival undoubtedly opens a door to a new world for her. Although Rika is willful and arrogant, Yuichi gradually falls in love with this innocent girl. However, in the gloomy past and confused future, can Yuichi stick to his choice?