In the summer of 1996, a 7-year-old girl named Aki Fukami was killed by a 14-year-old boy named Fumiya Misaki. The "Mikazuki Lake Incident" that shocked the whole society led to the tragedy of both families. 15 years later, Aki's brother Yoki (Eita) and his father Tatsuhiko (Akira Emoto) run a fishing ground in a remote corner. Tatsuhiko is obsessed with his daughter's tragedy. He learned that Fumiya had been released from prison 8 years ago. All signs indicate that the "boy A" of that year had no intention of repenting. Tatsuhiko died of a terminal illness, and Yoki accepted the request to avenge his friend Fumiya. At this moment, a girl with panic and loss visited Yoki. She was Fumiya's sister Futaba (Hikari Manshima). She and her family have been carrying the notoriety of the perpetrators for many years and have experienced countless hardships. Fate has tied the two men and women who should have been in opposition together. They will face this cruel past and present together with their respective families...