17岁的青葱时节，内向纯洁的少女小优（宫崎葵 饰）与放弃了棒球转而练习吉他的佑介（瑛太 饰）成为好朋友。她喜欢在课堂偷偷瞄着男孩的侧影，用笔画下对方的漫画形象；也喜欢每日陪伴他在河堤边练习，哼唱着同一段旋律。纵使心里多么喜欢，却无法将那三个字勇敢说出口。女孩小小的倔强与别扭，使两个年轻人错失了向彼此迈进一步的机会。另一方面，优的姐姐不久前刚刚与恋人生离死别，她的出现似乎使三人之间的关系微妙难测。此去经年，当优（永作博美 饰）和佑介（西岛秀俊 饰）再次见面，可曾想起当年河堤旁的梦幻岁月…… 　　本片荣获蒙特利尔国际电影节最佳导演奖。A high school student named Yu has a crush on one of her classmates, Yosuke. The boy spends most of his time sitting outside and playing his guitar, and Yu sits nearby and listens. One day, however, a terrible tragedy occurs, and the two do not see each other again for many years.