极有游泳天赋的10岁男孩左左，在青少年游泳界里斩获无数荣誉，但却因为引人嫉妒而遭遇校园欺凌，导致双腿受伤无法继续游泳。伤心的左左选择离开校游泳队，结束了自己未来本应充满希望的泳将生活。正在他意志消沉的时候，左左遇到了一条人鱼，他提出愿意用自己的尾巴交换左左的双腿，但已经失去信心的左左拒绝了。人鱼发誓一定要让左左再次回到赛场…… 主人公左左，虽然在一开始因为遭遇“校园欺凌”而失去了对人生的信念，但最后在友情的陪伴下重获信心，找寻新的希望，让人生重新走上正轨。这是一个以悲情开头、带着积极向上心态结束的正能量故事。 A talented 10-year-old boy, Zuo Zuo, has won numerous awards in the youth swimming competition. But he has been envied by his schoolmates. Bullying has resulted in injuries to both legs that prevent him from continuing to swim. Zuo Zuo is heartbroken and chooses to leave the school swim team.Zuo Zuo encounters a mermaid who offers to trade his tail for Zuo Zuo's legs.