After facing an irresistible change, what is she? Still him? Two women with different personalities have unexpectedly become the best sisters - He Xizhen, Liu Wanting, who like the above students at the same time, but in fact Wen Haosheng has long noticed Liu Wanting, in the hope of his friend, Yu Ting When the twins entered the relationship, the three also formed an intimate triangular relationship until an accident caused Wan Ting to discover that she had a double sexuality, and at this moment she must choose to live as one of the genders. Wan Ting unexpectedly refused to let the twins and Xi Zhen get caught off guard. After many years, Xi Zhen and the twins appeared a pure-looking boy, Liu Ting.

◆《月鱼》是直木奖得主、书店大奖得主三浦紫苑人气佳作！
◆三浦紫苑是被宫崎骏称赞不已的才女作家。
◆三浦紫苑在29岁获得有日本文坛“奥斯卡”之称的直木奖，35岁获得书店大奖，赢得日本书店店员一致好评。
◆写冷门职业比她还清新有趣的作家，至今没有出现！
◆继《多田便利屋》《编舟记》《强风吹拂》后，三浦紫苑书写旧书世界的友情岁月。
◆《月鱼》细腻勾勒了家庭与友谊，成长与救赎。故事娓娓道来，让人回味无穷。
◆越是旧的东西越值得珍惜，朋友也是如此。
这是两个年轻人如何重拾友谊的故事。
因为一册稀有的旧书，两个家庭支离破碎，原本亲密无间的少年再也无法坦诚相对。时光缓缓流逝，他们的人生道路看似波澜不惊，却一直暗流涌动。忘不了的往事，回不去的童年，填补不了的心灵裂缝，无时无刻不在纠缠着他们。
我们总是追悔莫及，也总是向往真挚的友情。也许，有时候我们只是需要给彼此一个原谅和救赎的机会。