"No matter what happens, we are a family." The world after "HiGH & LOW THE WORST". After Arata returns, the six childhood friends in the Kibogaoka community gather together after a long absence. The innocent atmosphere maker Kaede Shixiong, the smart and always top-scoring Seiji, the aggressive and rude "Orochi brothers" of Shinya and Masaya, the naughty and competitive Madoka, and the shy Arata. The six people have distinct personalities but a deep bond. 10 years ago today, which was also Seiji's birthday, he buried a time capsule containing a letter to himself 10 years later in a park near the community. On that day 10 years later, without anyone calling for help, the six people miraculously gathered together naturally. Under the night sky, they read the letters and talked about nostalgic topics. They looked at their current photos, wrote letters to themselves 10 years later, and buried the time capsule in the same place. However, after each of them set out on their journey home, a sudden tragedy occurred-