Takashi and four of his classmates, fourth-grade students, cannot succeed in doing a back pullover around a horizontal bar. Their gym teacher warns them: they have one week to succeed; if they resign now, then, tomorrow, facing life difficulties, they will always run away and become bums. Furthermore, all five must succeed, if one of them cannot do it, then all of them fail. Takashi is really worried and wonders if he won't be always the loser who couldn't succeed in the back pullover bar exercise.

日语里『夏天结束了』这句话，绝对不能用字面意思理解，里面包含了多少不可言说的含义，那是一夜长大的意思，是恋爱无疾而终的预兆，是青春消失殆尽的季节，是从梦想跌入到现实的分界点，是失去童真变成大人的夜晚，也是人生从充满期待的未知陷落到无可改变的已知的无所适从。

Takashi y cuatro de sus compañeros de escuela no son capaces de girar en la barra del gimnasio. Su profesor les da un ultimátum: si quieren aprobar, deberán superar esa dificultad; pero si uno de ellos fracasa, suspenderán los cinco.