Fujima Wu (voiced by Mashima Shinosuke) has a special ability to go back to the past. His mother, Sashiko (voiced by Gao Yamannan), was killed. Once trusted friend Shirayuki (voiced by Daosuke Mashima) is about to be sentenced to death as the real killer of children's serial murders. At this juncture, Wu suddenly returned to 1988 and returned to the primary school where he was studying at that time. At that time, the classmate Jiayue Jiayue (voiced by Yumubi) and Hiromi Yamada (voiced by Hiroshi Yamada) who died in the Yumubi case had not yet been killed, and Wu was determined to use his ability to protect the safety of Jiayu and Hiromi, cleanse the grievances of Bird run, and find the real culprit. Under Wu's efforts, the gloomy and withdrawn Jiadai finally opened his mind to him, and the two formed a deep friendship. Soon, the day of the case came, and the boundless night passed. When the light came, could Wu see Jiadai's innocent smiling face again?