Kagerou Daze, Vol. 4 (light novel): The Missing Children

A certain boy and girl meet on a certain endless summer day. They thought they were alone, misunderstood by everyone, but the powers they hold in their eyes lead them to a group that does understand them: the Mekakushi-dan. They're not alone anymore, but now they have a new mystery to solve: What is the phenomenon of the "kagerou daze," and who is the shadowy figure behind it?