Zwei Trigger - Orthros
Endlessly, wandering... surely, for all eternity.
In this town—that enjoyed explosive growth over the last ten years or so—the number of missing persons is several times the national average.
Having been disquieted by the disappearence of his sister-figure — Akizuki Kaname; Kurusu Yuuma has been searching for her, becoming entangled in a mystery.
Takanashi Shin'ya, in order to save Akesaka Touka, who suffers from a mysterious illness of unknown cause; investigates the truth of the spiriting away, which she too was once a victim of. This leads to him facing off with paranormal existences.
Now, the iron will of two boys shall become the trigger that lays bare the darkness that lurks within the city――