Since unexplained "grey domain phenomena" have appeared one after another around the world, the boundaries of reality have begun to loosen: sounds echo repeatedly in deserted streets; abandoned facilities activate themselves in the middle of the night; memories are rearranged by some invisible mechanism. Human society seems to be being slightly but continuously rewritten by an invisible hand.
The temporarily established "Return to Zero Echo Center" was forced to take over these spreading anomalies.
Lin Yu, an ordinary to somewhat transparent newcomer to the archives, "synchronized" with an unknown signal during an investigation incident, and became the center's focus - and was therefore pushed into the core investigation team. With in-depth investigations one after another, they discovered that these anomalies did not exist in isolation, but were like echoes from the same source——
Echoes are calling, rules are being reset, and "return to zero" is approaching.
