The story follows Michio, a fourth-grader who lives with his parents and younger sister Mika. On the last day of school, Michio goes to visit his absent classmate S to deliver his homework and a bribe. But when he arrives, he finds S's dead body with a rope around his neck.

However, when Michio's teacher and the police arrive, the body disappears without a trace. A week later, a spider claiming to be the reincarnation of S appears before Michio and reveals the identity of the killer. He asks Michio and Mika to find his body. As they dig deeper into the case, they discover that S's story may not be entirely true.

This is the physical copy of The Summer When Sunflowers Don't Bloom novel.