Refrain of the Cicada Shell

In the summer of his second year of high school, Sou Otogiri gains the power to turn back time to save his childhood friend, Tamako Otodama, who died in an accident. However, this power comes from a 'contract' with a black shadow that appears in his dreams. The shadow says: 'Give me your most precious memory.' Sou nods without hesitation. He returns to three days before Tamako's death. She is still alive, smiling. Waving her skirt, she comes to Sou's house every morning. That ordinary scenery