Naihe is an elf born of thousands of years of tears in Meng Po's soup. He grew up by the Naihe Bridge since childhood. He doesn't understand love, but he has witnessed Meng Po's obsession with Chai Daohuang for thousands of years. A plague caused by monsters swept across the world. As the chosen savior, Naihe descended to earth and was reincarnated as the daughter of a merchant in Chang'an in order to quell the disaster and help Po Meng find her old friend.
When she was still young, she met the destined Master Bai and became a member of the Kunlun Sect, changing her name to Ziying. Here, she met the hard-spoken and soft-hearted senior brother Zi Yuan, the dark-hearted and gentle third senior brother Zi Mo, and even the second senior senior brother Zi Yan who fell in love with her at first sight and guarded her everywhere. Ziyan warms up the ignorant Naihe in a clumsy and sincere way, and the two gradually fall in love with each other in their daily interactions.
As the plague spreads, all life in the world is devastated, and Naihe's mortal parents are also in deep crisis. The Kunlun Sect told them that only by recovering the six ancient plague books can the disaster be eradicated. With the dual mission of saving the common people and fulfilling Meng Po's wish, Nai He embarked on a journey with Zi Yan and other three senior brothers, traveling to the Turks, the Central Plains, the Western Regions and other places, fighting monsters, breaking the obstruction of the ancient book boy, and uncovering the thousand-year past of the Red Buddha Immortal Lord.
Along the way, Naihe gradually understands the joys and sorrows of the world, understands Po Meng's obsession, understands the true meaning of love through Ziyan's persistence, and grows from an ignorant and cruel underworld elf to a responsible savior. The whereabouts of Chai Daohuang and the conspiracy behind the plague gradually emerged in this adventure that spanned Yin and Yang.
