You Xian Ku (Chinese: ; roughly 'Journey to the Fairy Grotto') is a famous Chinese story from the "Legends of the Tang Dynasty", written by Zhang Zhuo .
Zhang Zhuo (Chinese:, born 658–730 CE), bestowed the honorary name of Wen Cheng, was a Tang dynasty jinshi, a former imperial censor, and a native of Luze, Shenzhou (now Shenxian county, Hebei province).
You Xian Ku is a story of the author's first-hand account visiting Heyuan (now Qinghai, Xinghai province), passing through Jishi mountain. "The days turn to nights, and the road is far. The horse is weary and the man tired" . He stayed in the fairy grotto and met two women by chance: Cui Shi Niang and Wu Sao, a widow. There they drank wine, wrote poetry, and joked around.
The entire text is written in Four-Six pianwen (parallel prose), mixed with bianwen, with rhymes and leisurely in style.
Some people called it a "new form of novel" . You Xian Ku is the Tang dynasty's earliest romance novel, based on the wanton lives of prostitutes first met by Tang scholars. It has had a profound influence on the love stories written by later generations. Although You Xian Ku had not been re-published in China for over a millennia, its popularity in Japan has never ceased. According to the Old Book of Tang, every time Japan sent an envoy to China during the Tang dynasty, they had to pay a lot to buy copies of the book. In the late Qing dynasty, the book was copied, reprinted in Japan and sent back to China.
In Bai Xianyong's novel Crystal Boys, the chapter "Journey to the Goblin Cave" (You Yao Ku,) is a parody of You Xian Ku.