Shotaro is an average kid, but when he’s with Sakurako, they find dead bodies. Under Sakurako’s orders, Shotaro unearths a human skull, leading to another mystery!

Shotaro and Sakurako find a skeleton in the mountains. The deceased’s granddaughter believes the police wrongly determined the death a suicide, and asks for the duo’s help.

Three of Isozaki’s students were inseparable until one vanished. As one of the remaining two disappears, Sakurako begins to assemble the bones of a more nebulous skeleton.