The story starts from the perspective of the protagonist, a reticent college dropout who works in his father's waste recycling company. One day Zhi Zhi met the boy Xiao in the swimming pool. When he came home in the evening, he gave his blind grandmother a lift. Grandma talked about her experience of traveling around the world when she was young, including Iguazu Falls in Spring. However, after being seriously ill and hospitalized, she confessed to the boys that she had never left Japan-she made up all the stories. She gave her passbook to her grandson, hoping to see the world for her, but her grandmother didn't know she didn't have much money. Huan, who couldn't bear to tell his grandmother the truth, thought he had no choice but to collect and synthesize all kinds of sound effects, imitate his travels around the world, and make a tape and please play it for his grandmother. Zhi himself was duty-bound to act as an assistant to Huan, collecting the sounds of waterfalls, the sea and the forest, sleeping in the wilderness or playing barefoot in the garage, playing wrestling games that only each other knew, and releasing their inner secret emotions. After a seemingly carefree period of time, Zhiji made a request: can we really travel around the world? For example, to see Iguazu Falls?