A mysterious disappearance of a girl happened at a camp held by an association for kids some years ago— Since then, the association didn't hold any action. And now, the association decided to hold an alumni. In order to look for "Yamauba," Honoka Inumaru witnessed at the camp, she joined the camp with Mizorogi, but…? Who Yamauba really is, and what happened to a girl who disappeared…!? A unique suspense story written by a genius duo! (Source: MU)