The male protagonist recalled a bizarre incident about his childhood home, and had an unspeakable secret related to his childhood playmate. After meeting the heroine 10 years later, the two accidentally discovered the legend of the hero's hometown through the records in a book. They were originally going to explore and play, but in the end, the legend and the hero's son were secretly connected. The heroine fainted inexplicably later. In order to understand Kaixin and save the heroine, the hero slowly dug out clues and sorted out scattered memories. Finally, he discovered a secret that spanned several eras, and found out the mastermind behind the scenes. Unexpectedly, a person he could not have imagined was involved. . .