A weekend afternoon.

It has been a given since they were children that Iori, the childhood friend, would be at the house. They spend time in the same room doing whatever they like, talking whenever the mood strikes. It was just another ordinary, mundane moment.

—That was why Guest let their guard down.

A smartphone left on the table. The screen displayed Zeta, which Guest had forgotten to close. Iori's fingers, which had casually drifted toward the device, suddenly stop.