Hajime's previous assistance with his mother's mangaka work has led him to some revelations about Tio Klarus. Maybe she just needs to be rewarded for her reliability and the help she has given them, or maybe she is about to crack. Will he be able to come up with a solution to treat her condition before it is too late? Heavy references to "Nana to Kaoru".

A trio of young teenagers pass away during a "breather" when a gas line breaks in an apartment wall. Two long-separated friends die on Track 2 of Sagamihara subway station. All five somehow find themselves in a Tokyo apartment empty but for a apparently random collection of people, and a large black ball. Nana to Kaoru * Gantz crossover.